From 4273b6ec1cb87d80eeeaca936a6b8ed0aafd96da Mon Sep 17 00:00:00 2001 From: John Mumm Date: Wed, 11 Jun 2014 11:56:32 -0400 Subject: [PATCH 01/19] Update README.md --- README.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/README.md b/README.md index 2d277e2625..70ffb744de 100644 --- a/README.md +++ b/README.md @@ -1,4 +1,4 @@ -# Airbnb JavaScript Style Guide() { +# TheLadders JavaScript Style Guide() { *A mostly reasonable approach to JavaScript* From ec85634798e9aee610b35264c10d4b3e79ae39b0 Mon Sep 17 00:00:00 2001 From: John Mumm Date: Wed, 11 Jun 2014 11:57:42 -0400 Subject: [PATCH 02/19] Update README.md --- README.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/README.md b/README.md index 70ffb744de..7fb34a9425 100644 --- a/README.md +++ b/README.md @@ -1,6 +1,6 @@ # TheLadders JavaScript Style Guide() { -*A mostly reasonable approach to JavaScript* +*A mostly reasonable approach to JavaScript (forked from Airbnb and modified)* ## Table of Contents From b6335ba7828478c120cc7d8e408efd8a2d4cf87e Mon Sep 17 00:00:00 2001 From: John Mumm Date: Thu, 12 Jun 2014 13:11:24 -0400 Subject: [PATCH 03/19] Modify style guide to match NLW practices --- README.md | 529 ++++++++++++++---------------------------------------- 1 file changed, 131 insertions(+), 398 deletions(-) diff --git a/README.md b/README.md index 7fb34a9425..887a481840 100644 --- a/README.md +++ b/README.md @@ -83,41 +83,6 @@ var item = {}; ``` - - Don't use [reserved words](http://es5.github.io/#x7.6.1) as keys. It won't work in IE8. [More info](https://github.com/airbnb/javascript/issues/61) - - ```javascript - // bad - var superman = { - default: { clark: 'kent' }, - private: true - }; - - // good - var superman = { - defaults: { clark: 'kent' }, - hidden: true - }; - ``` - - - Use readable synonyms in place of reserved words. - - ```javascript - // bad - var superman = { - class: 'alien' - }; - - // bad - var superman = { - klass: 'alien' - }; - - // good - var superman = { - type: 'alien' - }; - ``` - **[⬆ back to top](#table-of-contents)** ## Arrays @@ -132,19 +97,6 @@ var items = []; ``` - - If you don't know array length use Array#push. - - ```javascript - var someStack = []; - - - // bad - someStack[someStack.length] = 'abracadabra'; - - // good - someStack.push('abracadabra'); - ``` - - When you need to copy an array use Array#slice. [jsPerf](http://jsperf.com/converting-arguments-to-an-array/7) ```javascript @@ -165,7 +117,7 @@ ```javascript function trigger() { - var args = Array.prototype.slice.call(arguments); + var args = Array.slice.call(arguments); ... } ``` @@ -175,20 +127,20 @@ ## Strings - - Use single quotes `''` for strings + - Use single quotes `""` for strings ```javascript // bad - var name = "Bob Parr"; + var name = 'Bob Parr'; // good - var name = 'Bob Parr'; + var name = "Bob Parr"; // bad - var fullName = "Bob " + this.lastName; + var fullName = 'Bob ' + this.lastName; // good - var fullName = 'Bob ' + this.lastName; + var fullName = "Bob " + this.lastName; ``` - Strings longer than 80 characters should be written across multiple lines using string concatenation. @@ -196,62 +148,18 @@ ```javascript // bad - var errorMessage = 'This is a super long error that was thrown because of Batman. When you stop to think about how Batman had anything to do with this, you would get nowhere fast.'; + var errorMessage = "This is a super long error that was thrown because of Batman. When you stop to think about how Batman had anything to do with this, you would get nowhere fast."; // bad - var errorMessage = 'This is a super long error that was thrown because \ + var errorMessage = "This is a super long error that was thrown because \ of Batman. When you stop to think about how Batman had anything to do \ with this, you would get nowhere \ - fast.'; - - // good - var errorMessage = 'This is a super long error that was thrown because ' + - 'of Batman. When you stop to think about how Batman had anything to do ' + - 'with this, you would get nowhere fast.'; - ``` - - - When programmatically building up a string, use Array#join instead of string concatenation. Mostly for IE: [jsPerf](http://jsperf.com/string-vs-array-concat/2). - - ```javascript - var items, - messages, - length, - i; - - messages = [{ - state: 'success', - message: 'This one worked.' - }, { - state: 'success', - message: 'This one worked as well.' - }, { - state: 'error', - message: 'This one did not work.' - }]; - - length = messages.length; - - // bad - function inbox(messages) { - items = '
    '; - - for (i = 0; i < length; i++) { - items += '
  • ' + messages[i].message + '
  • '; - } - - return items + '
'; - } + fast."; // good - function inbox(messages) { - items = []; - - for (i = 0; i < length; i++) { - items[i] = messages[i].message; - } - - return '
  • ' + items.join('
  • ') + '
'; - } + var errorMessage = "This is a super long error that was thrown because " + + "of Batman. When you stop to think about how Batman had anything to do " + + "with this, you would get nowhere fast."; ``` **[⬆ back to top](#table-of-contents)** @@ -274,18 +182,18 @@ // immediately-invoked function expression (IIFE) (function() { - console.log('Welcome to the Internet. Please follow me.'); + console.log("Welcome to the Internet. Please follow me."); })(); ``` - - Never declare a function in a non-function block (if, while, etc). Assign the function to a variable instead. Browsers will allow you to do it, but they all interpret it differently, which is bad news bears. + - Never declare a function in a non-function block (if, while, etc). Assign the function to a variable instead. Browsers will allow you to do it, but they all interpret it differently, which is bad. - **Note:** ECMA-262 defines a `block` as a list of statements. A function declaration is not a statement. [Read ECMA-262's note on this issue](http://www.ecma-international.org/publications/files/ECMA-ST/Ecma-262.pdf#page=97). ```javascript // bad if (currentUser) { function test() { - console.log('Nope.'); + console.log("Nope."); } } @@ -293,7 +201,7 @@ var test; if (currentUser) { test = function test() { - console.log('Yup.'); + console.log("Yup."); }; } ``` @@ -327,7 +235,7 @@ }; // bad - var isJedi = luke['jedi']; + var isJedi = luke["jedi"]; // good var isJedi = luke.jedi; @@ -345,7 +253,7 @@ return luke[prop]; } - var isJedi = getProp('jedi'); + var isJedi = getProp("jedi"); ``` **[⬆ back to top](#table-of-contents)** @@ -353,7 +261,7 @@ ## Variables - - Always use `var` to declare variables. Not doing so will result in global variables. We want to avoid polluting the global namespace. Captain Planet warned us of that. + - Always use `var` to declare variables. Not doing so will result in global variables. We want to avoid polluting the global namespace. ```javascript // bad @@ -363,40 +271,18 @@ var superPower = new SuperPower(); ``` - - Use one `var` declaration for multiple variables and declare each variable on a newline. + - Use separate `var` declarations for multiple variables and declare each variable on a newline. ```javascript // bad - var items = getItems(); - var goSportsTeam = true; - var dragonball = 'z'; - - // good var items = getItems(), goSportsTeam = true, - dragonball = 'z'; - ``` - - - Declare unassigned variables last. This is helpful when later on you might need to assign a variable depending on one of the previous assigned variables. - - ```javascript - // bad - var i, len, dragonball, - items = getItems(), - goSportsTeam = true; - - // bad - var i, items = getItems(), - dragonball, - goSportsTeam = true, - len; + dragonball = "z"; // good - var items = getItems(), - goSportsTeam = true, - dragonball, - length, - i; + var items = getItems(); + var goSportsTeam = true; + var dragonball = "z"; ``` - Assign variables at the top of their scope. This helps avoid issues with variable declaration and assignment hoisting related issues. @@ -405,13 +291,13 @@ // bad function() { test(); - console.log('doing stuff..'); + console.log("doing stuff.."); //..other stuff.. var name = getName(); - if (name === 'test') { + if (name === "test") { return false; } @@ -423,11 +309,11 @@ var name = getName(); test(); - console.log('doing stuff..'); + console.log("doing stuff.."); //..other stuff.. - if (name === 'test') { + if (name === "test") { return false; } @@ -490,48 +376,6 @@ } ``` - - Anonymous function expressions hoist their variable name, but not the function assignment. - - ```javascript - function example() { - console.log(anonymous); // => undefined - - anonymous(); // => TypeError anonymous is not a function - - var anonymous = function() { - console.log('anonymous function expression'); - }; - } - ``` - - - Named function expressions hoist the variable name, not the function name or the function body. - - ```javascript - function example() { - console.log(named); // => undefined - - named(); // => TypeError named is not a function - - superPower(); // => ReferenceError superPower is not defined - - var named = function superPower() { - console.log('Flying'); - }; - } - - // the same is true when the function name - // is the same as the variable name. - function example() { - console.log(named); // => undefined - - named(); // => TypeError named is not a function - - var named = function named() { - console.log('named'); - } - } - ``` - - Function declarations hoist their name and the function body. ```javascript @@ -539,7 +383,7 @@ superPower(); // => Flying function superPower() { - console.log('Flying'); + console.log("Flying"); } } ``` @@ -549,7 +393,6 @@ **[⬆ back to top](#table-of-contents)** - ## Conditional Expressions & Equality - Use `===` and `!==` over `==` and `!=`. @@ -560,7 +403,7 @@ + **Null** evaluates to **false** + **Booleans** evaluate to **the value of the boolean** + **Numbers** evaluate to **false** if **+0, -0, or NaN**, otherwise **true** - + **Strings** evaluate to **false** if an empty string `''`, otherwise **true** + + **Strings** evaluate to **false** if an empty string `""`, otherwise **true** ```javascript if ([0]) { @@ -573,7 +416,7 @@ ```javascript // bad - if (name !== '') { + if (name !== "") { // ...stuff... } @@ -593,6 +436,25 @@ } ``` + - These shortcuts should not be used when checking for the existence of a property on an object. + + ```javascript + // bad - checks truthiness of value of the property, not for the existence of the property + if (someObject.someProperty) { + // ...stuff... + } + + // good - when checking if a property exists on an object or in its prototype chain + if ("someProperty" in someObject) { + // ...stuff... + } + + // good - when checking if a property exists on an object instance + if (someObject.hasOwnProperty("someProperty")) { + // ...stuff... + } + ``` + - For more information see [Truth Equality and JavaScript](http://javascriptweblog.wordpress.com/2011/02/07/truth-equality-and-javascript/#more-2108) by Angus Croll **[⬆ back to top](#table-of-contents)** @@ -629,6 +491,7 @@ ## Comments + *NOTE* HOW SHOULD WE DO THIS? - Use `/** ... */` for multiline comments. Include a description, specify types and values for all parameters and return values. ```javascript @@ -674,23 +537,24 @@ // bad function getType() { console.log('fetching type...'); - // set the default type to 'no type' - var type = this._type || 'no type'; + // set the default type to "no type" + var type = this._type || "no type"; return type; } // good function getType() { - console.log('fetching type...'); + console.log("fetching type..."); - // set the default type to 'no type' - var type = this._type || 'no type'; + // set the default type to "no type" + var type = this._type || "no type"; return type; } ``` + *NOTE* DO WE WANT TO START FOLLOWING THIS PRACTICE? - Prefixing your comments with `FIXME` or `TODO` helps other developers quickly understand if you're pointing out a problem that needs to be revisited, or if you're suggesting a solution to the problem that needs to be implemented. These are different than regular comments because they are actionable. The actions are `FIXME -- need to figure this out` or `TODO -- need to implement`. - Use `// FIXME:` to annotate problems @@ -722,22 +586,22 @@ ## Whitespace - - Use soft tabs set to 2 spaces + - Use soft tabs set to 4 spaces ```javascript // bad function() { - ∙∙∙∙var name; + ∙var name; } // bad function() { - ∙var name; + ∙∙var name; } // good function() { - ∙∙var name; + ∙∙∙∙var name; } ``` @@ -746,24 +610,24 @@ ```javascript // bad function test(){ - console.log('test'); + console.log("test"); } // good function test() { - console.log('test'); + console.log("test"); } // bad - dog.set('attr',{ - age: '1 year', - breed: 'Bernese Mountain Dog' + dog.set("attr",{ + age: "1 year", + breed: "Bernese Mountain Dog" }); // good - dog.set('attr', { - age: '1 year', - breed: 'Bernese Mountain Dog' + dog.set("attr", { + age: "1 year", + breed: "Bernese Mountain Dog" }); ``` @@ -777,6 +641,7 @@ var x = y + 5; ``` + *NOTE* SHOULD WE FOLLOW THIS PRACTICE? - End files with a single newline character. ```javascript @@ -805,30 +670,30 @@ ```javascript // bad - $('#items').find('.selected').highlight().end().find('.open').updateCount(); + $("#items").find(".selected").highlight().end().find(".open").updateCount(); // good - $('#items') - .find('.selected') + $("#items") + .find(".selected") .highlight() .end() - .find('.open') + .find(".open") .updateCount(); // bad - var leds = stage.selectAll('.led').data(data).enter().append('svg:svg').class('led', true) - .attr('width', (radius + margin) * 2).append('svg:g') - .attr('transform', 'translate(' + (radius + margin) + ',' + (radius + margin) + ')') + var leds = stage.selectAll(".led").data(data).enter().append("svg:svg").class("led", true) + .attr("width", (radius + margin) * 2).append('svg:g') + .attr("transform", "translate(" + (radius + margin) + "," + (radius + margin) + ")") .call(tron.led); // good - var leds = stage.selectAll('.led') + var leds = stage.selectAll(".led") .data(data) - .enter().append('svg:svg') - .class('led', true) + .enter().append("svg:svg") + .class("led", true) .attr('width', (radius + margin) * 2) - .append('svg:g') - .attr('transform', 'translate(' + (radius + margin) + ',' + (radius + margin) + ')') + .append("svg:g") + .attr("transform", "translate(" + (radius + margin) + "," + (radius + margin) + ")") .call(tron.led); ``` @@ -851,49 +716,21 @@ // bad var hero = { - firstName: 'Bob' - , lastName: 'Parr' - , heroName: 'Mr. Incredible' - , superPower: 'strength' + firstName: "Bob" + , lastName: "Parr" + , heroName: "Mr. Incredible" + , superPower: "strength" }; // good var hero = { - firstName: 'Bob', - lastName: 'Parr', - heroName: 'Mr. Incredible', - superPower: 'strength' + firstName: "Bob", + lastName: "Parr", + heroName: "Mr. Incredible", + superPower: "strength" }; ``` - - Additional trailing comma: **Nope.** This can cause problems with IE6/7 and IE9 if it's in quirksmode. Also, in some implementations of ES3 would add length to an array if it had an additional trailing comma. This was clarified in ES5 ([source](http://es5.github.io/#D)): - - > Edition 5 clarifies the fact that a trailing comma at the end of an ArrayInitialiser does not add to the length of the array. This is not a semantic change from Edition 3 but some implementations may have previously misinterpreted this. - - ```javascript - // bad - var hero = { - firstName: 'Kevin', - lastName: 'Flynn', - }; - - var heroes = [ - 'Batman', - 'Superman', - ]; - - // good - var hero = { - firstName: 'Kevin', - lastName: 'Flynn' - }; - - var heroes = [ - 'Batman', - 'Superman' - ]; - ``` - **[⬆ back to top](#table-of-contents)** @@ -904,19 +741,19 @@ ```javascript // bad (function() { - var name = 'Skywalker' + var name = "Skywalker" return name })() // good (function() { - var name = 'Skywalker'; + var name = "Skywalker"; return name; })(); // good ;(function() { - var name = 'Skywalker'; + var name = "Skywalker"; return name; })(); ``` @@ -933,22 +770,22 @@ // => this.reviewScore = 9; // bad - var totalScore = this.reviewScore + ''; + var totalScore = this.reviewScore + ""; // good - var totalScore = '' + this.reviewScore; + var totalScore = "" + this.reviewScore; // bad - var totalScore = '' + this.reviewScore + ' total score'; + var totalScore = "" + this.reviewScore + " total score"; // good - var totalScore = this.reviewScore + ' total score'; + var totalScore = this.reviewScore + " total score"; ``` - Use `parseInt` for Numbers and always with a radix for type casting. ```javascript - var inputValue = '4'; + var inputValue = "4"; // bad var val = new Number(inputValue); @@ -1031,14 +868,14 @@ var this_is_my_object = {}; function c() {} var u = new user({ - name: 'Bob Parr' + name: "Bob Parr" }); // good var thisIsMyObject = {}; function thisIsMyFunction() {} var user = new User({ - name: 'Bob Parr' + name: "Bob Parr" }); ``` @@ -1051,7 +888,7 @@ } var bad = new user({ - name: 'nope' + name: "nope" }); // good @@ -1060,19 +897,20 @@ } var good = new User({ - name: 'yup' + name: "yup" }); ``` + *NOTE* WE DON'T DO THIS, BUT MAYBE WE SHOULD? - Use a leading underscore `_` when naming private properties ```javascript // bad - this.__firstName__ = 'Panda'; - this.firstName_ = 'Panda'; + this.__firstName__ = "Panda"; + this.firstName_ = "Panda"; // good - this._firstName = 'Panda'; + this._firstName = "Panda"; ``` - When saving a reference to `this` use `_this`. @@ -1103,20 +941,6 @@ } ``` - - Name your functions. This is helpful for stack traces. - - ```javascript - // bad - var log = function(msg) { - console.log(msg); - }; - - // good - var log = function log(msg) { - console.log(msg); - }; - ``` - - **Note:** IE8 and below exhibit some quirks with named function expressions. See [http://kangax.github.io/nfe/](http://kangax.github.io/nfe/) for more info. **[⬆ back to top](#table-of-contents)** @@ -1124,21 +948,14 @@ ## Accessors - - Accessor functions for properties are not required - - If you do make accessor functions use getVal() and setVal('hello') + - Accessor functions on Backbone models do not use the getVal() pattern. ```javascript // bad - dragon.age(); - - // good dragon.getAge(); - // bad - dragon.age(25); - // good - dragon.setAge(25); + dragon.age(); ``` - If the property is a boolean, use isVal() or hasVal() @@ -1155,24 +972,6 @@ } ``` - - It's okay to create get() and set() functions, but be consistent. - - ```javascript - function Jedi(options) { - options || (options = {}); - var lightsaber = options.lightsaber || 'blue'; - this.set('lightsaber', lightsaber); - } - - Jedi.prototype.set = function(key, val) { - this[key] = val; - }; - - Jedi.prototype.get = function(key) { - return this[key]; - }; - ``` - **[⬆ back to top](#table-of-contents)** @@ -1182,27 +981,27 @@ ```javascript function Jedi() { - console.log('new jedi'); + console.log("new jedi"); } // bad Jedi.prototype = { - fight: function fight() { - console.log('fighting'); + fight: function() { + console.log("fighting"); }, - block: function block() { - console.log('blocking'); + block: function() { + console.log("blocking"); } }; // good - Jedi.prototype.fight = function fight() { - console.log('fighting'); + Jedi.prototype.fight = function() { + console.log("fighting"); }; - Jedi.prototype.block = function block() { - console.log('blocking'); + Jedi.prototype.block = function() { + console.log("blocking"); }; ``` @@ -1240,13 +1039,12 @@ .setHeight(20); ``` - - It's okay to write a custom toString() method, just make sure it works successfully and causes no side effects. ```javascript function Jedi(options) { options || (options = {}); - this.name = options.name || 'no name'; + this.name = options.name || "no name"; } Jedi.prototype.getName = function getName() { @@ -1254,7 +1052,7 @@ }; Jedi.prototype.toString = function toString() { - return 'Jedi - ' + this.getName(); + return "Jedi - " + this.getName(); }; ``` @@ -1263,62 +1061,12 @@ ## Events - - When attaching data payloads to events (whether DOM events or something more proprietary like Backbone events), pass a hash instead of a raw value. This allows a subsequent contributor to add more data to the event payload without finding and updating every handler for the event. For example, instead of: - - ```js - // bad - $(this).trigger('listingUpdated', listing.id); - - ... - - $(this).on('listingUpdated', function(e, listingId) { - // do something with listingId - }); - ``` - - prefer: - - ```js - // good - $(this).trigger('listingUpdated', { listingId : listing.id }); - - ... - - $(this).on('listingUpdated', function(e, data) { - // do something with data.listingId - }); - ``` - **[⬆ back to top](#table-of-contents)** ## Modules - - The module should start with a `!`. This ensures that if a malformed module forgets to include a final semicolon there aren't errors in production when the scripts get concatenated. [Explanation](https://github.com/airbnb/javascript/issues/44#issuecomment-13063933) - - The file should be named with camelCase, live in a folder with the same name, and match the name of the single export. - - Add a method called `noConflict()` that sets the exported module to the previous version and returns this one. - - Always declare `'use strict';` at the top of the module. - - ```javascript - // fancyInput/fancyInput.js - - !function(global) { - 'use strict'; - - var previousFancyInput = global.FancyInput; - - function FancyInput(options) { - this.options = options || {}; - } - - FancyInput.noConflict = function noConflict() { - global.FancyInput = previousFancyInput; - return FancyInput; - }; - - global.FancyInput = FancyInput; - }(this); - ``` + - Always declare `"use strict";` at the top of the module. **[⬆ back to top](#table-of-contents)** @@ -1329,10 +1077,10 @@ ```javascript // bad - var sidebar = $('.sidebar'); + var sidebar = ".sidebar"); // good - var $sidebar = $('.sidebar'); + var $sidebar = ".sidebar"); ``` - Cache jQuery lookups. @@ -1340,30 +1088,29 @@ ```javascript // bad function setSidebar() { - $('.sidebar').hide(); + ".sidebar").hide(); // ...stuff... - $('.sidebar').css({ - 'background-color': 'pink' + ".sidebar").css({ + "background-color": "pink" }); } // good function setSidebar() { - var $sidebar = $('.sidebar'); + var $sidebar = ".sidebar"); $sidebar.hide(); // ...stuff... $sidebar.css({ - 'background-color': 'pink' + "background-color": "pink" }); } ``` - - For DOM queries use Cascading `$('.sidebar ul')` or parent > child `$('.sidebar > ul')`. [jsPerf](http://jsperf.com/jquery-find-vs-context-sel/16) - - Use `find` with scoped jQuery object queries. + - Scope jQuery object queries to Backbone view using this.$el.find() ```javascript // bad @@ -1373,10 +1120,10 @@ $('.sidebar').find('ul').hide(); // good - $('.sidebar ul').hide(); + this.$el.find('.sidebar ul').hide(); // good - $('.sidebar > ul').hide(); + this.$el.find('.sidebar > ul').hide(); // good $sidebar.find('ul').hide(); @@ -1479,7 +1226,7 @@ ## In the Wild - This is a list of organizations that are using this style guide. Send us a pull request or open an issue and we'll add you to the list. + This is a list of organizations that are using variations of the Airbnb style guide. - **Aan Zee**: [AanZee/javascript](https://github.com/AanZee/javascript) - **Airbnb**: [airbnb/javascript](https://github.com/airbnb/javascript) @@ -1510,20 +1257,6 @@ - **Zillow**: [zillow/javascript](https://github.com/zillow/javascript) - **ZocDoc**: [ZocDoc/javascript](https://github.com/ZocDoc/javascript) -## Translation - - This style guide is also available in other languages: - - - :de: **German**: [timofurrer/javascript-style-guide](https://github.com/timofurrer/javascript-style-guide) - - :jp: **Japanese**: [mitsuruog/javacript-style-guide](https://github.com/mitsuruog/javacript-style-guide) - - :br: **Portuguese**: [armoucar/javascript-style-guide](https://github.com/armoucar/javascript-style-guide) - - :cn: **Chinese**: [adamlu/javascript-style-guide](https://github.com/adamlu/javascript-style-guide) - - :es: **Spanish**: [paolocarrasco/javascript-style-guide](https://github.com/paolocarrasco/javascript-style-guide) - - :kr: **Korean**: [tipjs/javascript-style-guide](https://github.com/tipjs/javascript-style-guide) - - :fr: **French**: [nmussy/javascript-style-guide](https://github.com/nmussy/javascript-style-guide) - - :ru: **Russian**: [uprock/javascript](https://github.com/uprock/javascript) - - :bg: **Bulgarian**: [borislavvv/javascript](https://github.com/borislavvv/javascript) - ## The JavaScript Style Guide Guide - [Reference](https://github.com/airbnb/javascript/wiki/The-JavaScript-Style-Guide-Guide) From 8e6687c6049619d5f90aca1d0c031eb4b148f6ad Mon Sep 17 00:00:00 2001 From: John Mumm Date: Thu, 12 Jun 2014 13:14:13 -0400 Subject: [PATCH 04/19] Fix typo --- README.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/README.md b/README.md index 887a481840..4590da2d2a 100644 --- a/README.md +++ b/README.md @@ -127,7 +127,7 @@ ## Strings - - Use single quotes `""` for strings + - Use double quotes `""` for strings ```javascript // bad From 6604880bec5aed35cf75ccece74bd694c5a359bd Mon Sep 17 00:00:00 2001 From: John Mumm Date: Thu, 12 Jun 2014 13:21:15 -0400 Subject: [PATCH 05/19] No space between arguments/parameters and enclosing parens for functions --- README.md | 24 ++++++++++++++++++++++-- 1 file changed, 22 insertions(+), 2 deletions(-) diff --git a/README.md b/README.md index 4590da2d2a..ceb61d76ca 100644 --- a/README.md +++ b/README.md @@ -186,6 +186,26 @@ })(); ``` + - Never leave space between parameters/arguments and enclosing parentheses. + + ```javascript + // bad + function imbibe( drink ) { + // ...stuff... + } + + // bad + imbibe( "seltzer" ); + + // good + function imbibe(drink) { + // ...stuff... + } + + // good + imbibe("seltzer"); + ``` + - Never declare a function in a non-function block (if, while, etc). Assign the function to a variable instead. Browsers will allow you to do it, but they all interpret it differently, which is bad. - **Note:** ECMA-262 defines a `block` as a list of statements. A function declaration is not a statement. [Read ECMA-262's note on this issue](http://www.ecma-international.org/publications/files/ECMA-ST/Ecma-262.pdf#page=97). @@ -271,7 +291,7 @@ var superPower = new SuperPower(); ``` - - Use separate `var` declarations for multiple variables and declare each variable on a newline. + - Use separate `var` declarations for multiple variables and declare each variable on a new line. ```javascript // bad @@ -524,7 +544,7 @@ } ``` - - Use `//` for single line comments. Place single line comments on a newline above the subject of the comment. Put an empty line before the comment. + - Use `//` for single line comments. Place single line comments on a new line above the subject of the comment. Put an empty line before the comment. ```javascript // bad From 3908d371c218e74c1741a6e816949b04305fc6ba Mon Sep 17 00:00:00 2001 From: John Mumm Date: Thu, 12 Jun 2014 13:30:36 -0400 Subject: [PATCH 06/19] Update linters --- README.md | 16 ++++++++-------- .../SublimeLinter/SublimeLinter.sublime-settings | 10 +++++----- linters/jshintrc | 8 ++++---- 3 files changed, 17 insertions(+), 17 deletions(-) diff --git a/README.md b/README.md index ceb61d76ca..a462dffbfa 100644 --- a/README.md +++ b/README.md @@ -556,7 +556,7 @@ // bad function getType() { - console.log('fetching type...'); + console.log("fetching type..."); // set the default type to "no type" var type = this._type || "no type"; @@ -702,7 +702,7 @@ // bad var leds = stage.selectAll(".led").data(data).enter().append("svg:svg").class("led", true) - .attr("width", (radius + margin) * 2).append('svg:g') + .attr("width", (radius + margin) * 2).append("svg:g") .attr("transform", "translate(" + (radius + margin) + "," + (radius + margin) + ")") .call(tron.led); @@ -711,7 +711,7 @@ .data(data) .enter().append("svg:svg") .class("led", true) - .attr('width', (radius + margin) * 2) + .attr("width", (radius + margin) * 2) .append("svg:g") .attr("transform", "translate(" + (radius + margin) + "," + (radius + margin) + ")") .call(tron.led); @@ -1134,19 +1134,19 @@ ```javascript // bad - $('ul', '.sidebar').hide(); + $("ul", ".sidebar").hide(); // bad - $('.sidebar').find('ul').hide(); + $(".sidebar").find("ul").hide(); // good - this.$el.find('.sidebar ul').hide(); + this.$el.find(".sidebar ul").hide(); // good - this.$el.find('.sidebar > ul').hide(); + this.$el.find(".sidebar > ul").hide(); // good - $sidebar.find('ul').hide(); + $sidebar.find("ul").hide(); ``` **[⬆ back to top](#table-of-contents)** diff --git a/linters/SublimeLinter/SublimeLinter.sublime-settings b/linters/SublimeLinter/SublimeLinter.sublime-settings index 12360f3f1c..18fa265518 100644 --- a/linters/SublimeLinter/SublimeLinter.sublime-settings +++ b/linters/SublimeLinter/SublimeLinter.sublime-settings @@ -1,5 +1,5 @@ /** - * Airbnb JSHint settings for use with SublimeLinter and Sublime Text 2. + * TheLadders JSHint settings for use with SublimeLinter and Sublime Text 2. * * 1. Install SublimeLinter at https://github.com/SublimeLinter/SublimeLinter * 2. Open user preferences for the SublimeLinter package in Sublime Text 2 @@ -43,8 +43,8 @@ // Suppress warnings about == null comparisons. "eqnull": true, - // Enforce tab width of 2 spaces. - "indent": 2, + // Enforce tab width of 4 spaces. + "indent": 4, // Prohibit use of a variable before it is defined. "latedef": true, @@ -52,8 +52,8 @@ // Require capitalized names for constructor functions. "newcap": true, - // Enforce use of single quotation marks for strings. - "quotmark": "single", + // Enforce use of double quotation marks for strings. + "quotmark": "double", // Prohibit trailing whitespace. "trailing": true, diff --git a/linters/jshintrc b/linters/jshintrc index d3b47148a8..d4f8010c99 100644 --- a/linters/jshintrc +++ b/linters/jshintrc @@ -28,8 +28,8 @@ // Suppress warnings about == null comparisons. "eqnull": true, - // Enforce tab width of 2 spaces. - "indent": 2, + // Enforce tab width of 4 spaces. + "indent": 4, // Prohibit use of a variable before it is defined. "latedef": true, @@ -37,8 +37,8 @@ // Require capitalized names for constructor functions. "newcap": true, - // Enforce use of single quotation marks for strings. - "quotmark": "single", + // Enforce use of double quotation marks for strings. + "quotmark": "double", // Prohibit trailing whitespace. "trailing": true, From 1ebf6b2613bd9c7ecc0cfe79e3522f7ac03f0e96 Mon Sep 17 00:00:00 2001 From: John Mumm Date: Thu, 12 Jun 2014 17:31:43 -0400 Subject: [PATCH 07/19] Update examples --- README.md | 171 ++++++++++++++++++++++++------------------------------ 1 file changed, 76 insertions(+), 95 deletions(-) diff --git a/README.md b/README.md index a462dffbfa..379e16c454 100644 --- a/README.md +++ b/README.md @@ -131,35 +131,16 @@ ```javascript // bad - var name = 'Bob Parr'; + var name = 'Immanuel Kant'; // good - var name = "Bob Parr"; + var name = "Immanuel Kant"; // bad - var fullName = 'Bob ' + this.lastName; + var fullName = 'Immanuel ' + this.lastName; // good - var fullName = "Bob " + this.lastName; - ``` - - - Strings longer than 80 characters should be written across multiple lines using string concatenation. - - Note: If overused, long strings with concatenation could impact performance. [jsPerf](http://jsperf.com/ya-string-concat) & [Discussion](https://github.com/airbnb/javascript/issues/40) - - ```javascript - // bad - var errorMessage = "This is a super long error that was thrown because of Batman. When you stop to think about how Batman had anything to do with this, you would get nowhere fast."; - - // bad - var errorMessage = "This is a super long error that was thrown because \ - of Batman. When you stop to think about how Batman had anything to do \ - with this, you would get nowhere \ - fast."; - - // good - var errorMessage = "This is a super long error that was thrown because " + - "of Batman. When you stop to think about how Batman had anything to do " + - "with this, you would get nowhere fast."; + var fullName = "Immanuel " + this.lastName; ``` **[⬆ back to top](#table-of-contents)** @@ -182,7 +163,7 @@ // immediately-invoked function expression (IIFE) (function() { - console.log("Welcome to the Internet. Please follow me."); + console.log("You want it to be one way... but it's the other way."); })(); ``` @@ -249,31 +230,31 @@ - Use dot notation when accessing properties. ```javascript - var luke = { - jedi: true, - age: 28 + var plato = { + athenian: true, + age: 30 }; // bad - var isJedi = luke["jedi"]; + var isAthenian = plato["athenian"]; // good - var isJedi = luke.jedi; + var isAthenian = plato.athenian; ``` - Use subscript notation `[]` when accessing properties with a variable. ```javascript - var luke = { - jedi: true, - age: 28 + var plato = { + athenian: true, + age: 30 }; function getProp(prop) { - return luke[prop]; + return plato[prop]; } - var isJedi = getProp("jedi"); + var isAthenian = getProp("athenian"); ``` **[⬆ back to top](#table-of-contents)** @@ -285,24 +266,24 @@ ```javascript // bad - superPower = new SuperPower(); + treatise = new Treatise(); // good - var superPower = new SuperPower(); + var treatise = new Treatise(); ``` - Use separate `var` declarations for multiple variables and declare each variable on a new line. ```javascript // bad - var items = getItems(), - goSportsTeam = true, - dragonball = "z"; + var books = getBooks(), + peaceful = true, + library = "Alexandria"; // good - var items = getItems(); - var goSportsTeam = true; - var dragonball = "z"; + var books = getBooks(); + var peaceful = true; + var library = "Alexandria"; ``` - Assign variables at the top of their scope. This helps avoid issues with variable declaration and assignment hoisting related issues. @@ -400,10 +381,10 @@ ```javascript function example() { - superPower(); // => Flying + read(); // logs "Human reason has the peculiar fate in one species of its cognitions..." - function superPower() { - console.log("Flying"); + function read() { + console.log("Human reason has the peculiar fate in one species of its cognitions..."); } } ``` @@ -639,15 +620,15 @@ } // bad - dog.set("attr",{ + falcon.set("attr",{ age: "1 year", - breed: "Bernese Mountain Dog" + breed: "Maltese" }); // good - dog.set("attr", { + falcon.set("attr", { age: "1 year", - breed: "Bernese Mountain Dog" + breed: "Maltese" }); ``` @@ -736,18 +717,18 @@ // bad var hero = { - firstName: "Bob" - , lastName: "Parr" - , heroName: "Mr. Incredible" - , superPower: "strength" + firstName: "Immanuel" + , lastName: "Kant" + , birthPlace: "Koenigsberg" + , masterWork: "The Critique of Pure Reason" }; // good var hero = { - firstName: "Bob", - lastName: "Parr", - heroName: "Mr. Incredible", - superPower: "strength" + firstName: "Immanuel", + lastName: "Kant", + birthPlace: "Koenigsberg", + masterWork: "The Critique of Pure Reason" }; ``` @@ -761,19 +742,19 @@ ```javascript // bad (function() { - var name = "Skywalker" + var name = "Ada" return name })() // good (function() { - var name = "Skywalker"; + var name = "Ada"; return name; })(); // good ;(function() { - var name = "Skywalker"; + var name = "Ada"; return name; })(); ``` @@ -888,14 +869,14 @@ var this_is_my_object = {}; function c() {} var u = new user({ - name: "Bob Parr" + name: "Ada Lovelace" }); // good var thisIsMyObject = {}; function thisIsMyFunction() {} var user = new User({ - name: "Bob Parr" + name: "Ada Lovelace" }); ``` @@ -972,22 +953,22 @@ ```javascript // bad - dragon.getAge(); + bowie.getAlbums(); // good - dragon.age(); + bowie.albums(); ``` - If the property is a boolean, use isVal() or hasVal() ```javascript // bad - if (!dragon.age()) { + if (!bowie.albums()) { return false; } // good - if (!dragon.hasAge()) { + if (!bowie.hasAlbums()) { return false; } ``` @@ -1000,28 +981,28 @@ - Assign methods to the prototype object, instead of overwriting the prototype with a new object. Overwriting the prototype makes inheritance impossible: by resetting the prototype you'll overwrite the base! ```javascript - function Jedi() { - console.log("new jedi"); + function Writer() { + console.log("new writer"); } // bad - Jedi.prototype = { - fight: function() { - console.log("fighting"); + Writer.prototype = { + procrastinate: function() { + console.log("procrastinating"); }, - block: function() { - console.log("blocking"); + dream: function() { + console.log("dreaming"); } }; // good - Jedi.prototype.fight = function() { - console.log("fighting"); + Writer.prototype.procrastinate = function() { + console.log("procrastinating"); }; - Jedi.prototype.block = function() { - console.log("blocking"); + Writer.prototype.dream = function() { + console.log("dreaming"); }; ``` @@ -1029,50 +1010,50 @@ ```javascript // bad - Jedi.prototype.jump = function() { - this.jumping = true; + Writer.prototype.resolve = function() { + this.madeResolution = true; return true; }; - Jedi.prototype.setHeight = function(height) { - this.height = height; + Writer.prototype.imagineMovingTo = function(destination) { + this.destination = destination; }; - var luke = new Jedi(); - luke.jump(); // => true - luke.setHeight(20) // => undefined + var roommate = new Writer(); + roommate.resolve(); // => true + roommate.imagineMovingTo("Paris") // => undefined // good - Jedi.prototype.jump = function() { - this.jumping = true; + Writer.prototype.resolve = function() { + this.madeResolution = true; return this; }; - Jedi.prototype.setHeight = function(height) { - this.height = height; + Writer.prototype.imagineMovingTo = function(destination) { + this.destination = destination; return this; }; - var luke = new Jedi(); + var roommate = new Writer(); - luke.jump() - .setHeight(20); + roommate.resolve() + .imagineMovingTo("Paris"); ``` - It's okay to write a custom toString() method, just make sure it works successfully and causes no side effects. ```javascript - function Jedi(options) { + function Writer(options) { options || (options = {}); this.name = options.name || "no name"; } - Jedi.prototype.getName = function getName() { + Writer.prototype.getName = function getName() { return this.name; }; - Jedi.prototype.toString = function toString() { - return "Jedi - " + this.getName(); + Writer.prototype.toString = function toString() { + return "Writer - " + this.getName(); }; ``` From df667256b8b8fb5a5f91a8a907a9c42b0c084f6f Mon Sep 17 00:00:00 2001 From: John Mumm Date: Thu, 12 Jun 2014 17:35:03 -0400 Subject: [PATCH 08/19] Remove inconsistent example --- README.md | 10 ---------- 1 file changed, 10 deletions(-) diff --git a/README.md b/README.md index 379e16c454..af01df4688 100644 --- a/README.md +++ b/README.md @@ -705,16 +705,6 @@ - Leading commas: **Nope.** ```javascript - // bad - var once - , upon - , aTime; - - // good - var once, - upon, - aTime; - // bad var hero = { firstName: "Immanuel" From 1e075976c1de483bb4012ce11aed4c9ba4cc3cfa Mon Sep 17 00:00:00 2001 From: John Mumm Date: Thu, 12 Jun 2014 17:38:05 -0400 Subject: [PATCH 09/19] Update name --- README.md | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/README.md b/README.md index af01df4688..78c5b0f564 100644 --- a/README.md +++ b/README.md @@ -897,11 +897,11 @@ ```javascript // bad - this.__firstName__ = "Panda"; - this.firstName_ = "Panda"; + this.__firstName__ = "Ada"; + this.firstName_ = "Ada"; // good - this._firstName = "Panda"; + this._firstName = "Ada"; ``` - When saving a reference to `this` use `_this`. From 99bb9979631152b403c274b5133d822dbc3ff992 Mon Sep 17 00:00:00 2001 From: John Mumm Date: Fri, 13 Jun 2014 14:23:25 -0400 Subject: [PATCH 10/19] Accept details about comment categories --- README.md | 10 ++-------- 1 file changed, 2 insertions(+), 8 deletions(-) diff --git a/README.md b/README.md index 78c5b0f564..80df6776d2 100644 --- a/README.md +++ b/README.md @@ -492,16 +492,13 @@ ## Comments - *NOTE* HOW SHOULD WE DO THIS? - - Use `/** ... */` for multiline comments. Include a description, specify types and values for all parameters and return values. + - Use `/** ... */` for multiline comments. ```javascript // bad // make() returns a new element // based on the passed in tag name // - // @param tag - // @return element function make(tag) { // ...stuff... @@ -514,8 +511,6 @@ * make() returns a new element * based on the passed in tag name * - * @param tag - * @return element */ function make(tag) { @@ -555,8 +550,7 @@ } ``` - *NOTE* DO WE WANT TO START FOLLOWING THIS PRACTICE? - - Prefixing your comments with `FIXME` or `TODO` helps other developers quickly understand if you're pointing out a problem that needs to be revisited, or if you're suggesting a solution to the problem that needs to be implemented. These are different than regular comments because they are actionable. The actions are `FIXME -- need to figure this out` or `TODO -- need to implement`. + - Prefixing your comments with FIXME, TODO, or HACK helps other developers quickly understand what kind of problem you're pointing out. These are different than regular comments because they are actionable. FIXME indicates that a problem that still needs a solution. TODO describes the form of a solution to a problem. HACK indicates a fast, suboptimal solution that should be improved. - Use `// FIXME:` to annotate problems From 7b160c1f20ecc6920fc27e318c17eb64b0a9d7d7 Mon Sep 17 00:00:00 2001 From: John Mumm Date: Fri, 13 Jun 2014 14:41:01 -0400 Subject: [PATCH 11/19] Remove unused rules --- README.md | 41 ++--------------------------------------- 1 file changed, 2 insertions(+), 39 deletions(-) diff --git a/README.md b/README.md index 80df6776d2..3f642dabd7 100644 --- a/README.md +++ b/README.md @@ -534,7 +534,7 @@ function getType() { console.log("fetching type..."); // set the default type to "no type" - var type = this._type || "no type"; + var type = this.type || "no type"; return type; } @@ -544,7 +544,7 @@ console.log("fetching type..."); // set the default type to "no type" - var type = this._type || "no type"; + var type = this.type || "no type"; return type; } @@ -636,31 +636,6 @@ var x = y + 5; ``` - *NOTE* SHOULD WE FOLLOW THIS PRACTICE? - - End files with a single newline character. - - ```javascript - // bad - (function(global) { - // ...stuff... - })(this); - ``` - - ```javascript - // bad - (function(global) { - // ...stuff... - })(this);↵ - ↵ - ``` - - ```javascript - // good - (function(global) { - // ...stuff... - })(this);↵ - ``` - - Use indentation when making long method chains. ```javascript @@ -886,18 +861,6 @@ }); ``` - *NOTE* WE DON'T DO THIS, BUT MAYBE WE SHOULD? - - Use a leading underscore `_` when naming private properties - - ```javascript - // bad - this.__firstName__ = "Ada"; - this.firstName_ = "Ada"; - - // good - this._firstName = "Ada"; - ``` - - When saving a reference to `this` use `_this`. ```javascript From 436f1facedc2e0e69d3f0de26b5ce151a9d21e3b Mon Sep 17 00:00:00 2001 From: John Mumm Date: Fri, 13 Jun 2014 14:48:49 -0400 Subject: [PATCH 12/19] Add rule for function declaration order --- README.md | 49 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 49 insertions(+) diff --git a/README.md b/README.md index 3f642dabd7..3795504999 100644 --- a/README.md +++ b/README.md @@ -187,6 +187,55 @@ imbibe("seltzer"); ``` + - Follow a top down flow for declaring functions. The code should read like a newspaper. + + ```javascript + // bad + function readNextPage() { + console.log("This is getting interesting..."); + } + + var Book = { + turnPage: readNextPage() + } + + // bad + function end() { + console.log("Oh no, a twist!"); + } + + function begin() { + console.log("What's going to happen next?"); + end(); + } + + function readBook() { + begin(); + } + + // good + var Book = { + turnPage: readNextPage() + } + + function readNextPage() { + console.log("This is getting interesting..."); + } + + // good + function readBook() { + begin(); + } + + function begin() { + console.log("What's going to happen next?"); + end(); + } + + function end() { + console.log("Oh no, a twist!"); + } + - Never declare a function in a non-function block (if, while, etc). Assign the function to a variable instead. Browsers will allow you to do it, but they all interpret it differently, which is bad. - **Note:** ECMA-262 defines a `block` as a list of statements. A function declaration is not a statement. [Read ECMA-262's note on this issue](http://www.ecma-international.org/publications/files/ECMA-ST/Ecma-262.pdf#page=97). From 3bab11674a4fc3eb226af3fbe82a9314613f6f56 Mon Sep 17 00:00:00 2001 From: John Mumm Date: Fri, 13 Jun 2014 14:49:59 -0400 Subject: [PATCH 13/19] Add missing ``` --- README.md | 1 + 1 file changed, 1 insertion(+) diff --git a/README.md b/README.md index 3795504999..c93ce5f72d 100644 --- a/README.md +++ b/README.md @@ -235,6 +235,7 @@ function end() { console.log("Oh no, a twist!"); } + ``` - Never declare a function in a non-function block (if, while, etc). Assign the function to a variable instead. Browsers will allow you to do it, but they all interpret it differently, which is bad. - **Note:** ECMA-262 defines a `block` as a list of statements. A function declaration is not a statement. [Read ECMA-262's note on this issue](http://www.ecma-international.org/publications/files/ECMA-ST/Ecma-262.pdf#page=97). From 3b754147a749dc29c5dde378f38e4244d59bfaa6 Mon Sep 17 00:00:00 2001 From: John Mumm Date: Sat, 14 Jun 2014 11:17:56 -0400 Subject: [PATCH 14/19] Convert two spaces to four spaces --- README.md | 1926 ++++++++++++++++++++++++++--------------------------- 1 file changed, 963 insertions(+), 963 deletions(-) diff --git a/README.md b/README.md index c93ce5f72d..1b6af23f02 100644 --- a/README.md +++ b/README.md @@ -5,271 +5,271 @@ ## Table of Contents - 1. [Types](#types) - 1. [Objects](#objects) - 1. [Arrays](#arrays) - 1. [Strings](#strings) - 1. [Functions](#functions) - 1. [Properties](#properties) - 1. [Variables](#variables) - 1. [Hoisting](#hoisting) - 1. [Conditional Expressions & Equality](#conditional-expressions--equality) - 1. [Blocks](#blocks) - 1. [Comments](#comments) - 1. [Whitespace](#whitespace) - 1. [Commas](#commas) - 1. [Semicolons](#semicolons) - 1. [Type Casting & Coercion](#type-casting--coercion) - 1. [Naming Conventions](#naming-conventions) - 1. [Accessors](#accessors) - 1. [Constructors](#constructors) - 1. [Events](#events) - 1. [Modules](#modules) - 1. [jQuery](#jquery) - 1. [ECMAScript 5 Compatibility](#ecmascript-5-compatibility) - 1. [Testing](#testing) - 1. [Performance](#performance) - 1. [Resources](#resources) - 1. [In the Wild](#in-the-wild) - 1. [Translation](#translation) - 1. [The JavaScript Style Guide Guide](#the-javascript-style-guide-guide) - 1. [Contributors](#contributors) - 1. [License](#license) + 1. [Types](#types) + 1. [Objects](#objects) + 1. [Arrays](#arrays) + 1. [Strings](#strings) + 1. [Functions](#functions) + 1. [Properties](#properties) + 1. [Variables](#variables) + 1. [Hoisting](#hoisting) + 1. [Conditional Expressions & Equality](#conditional-expressions--equality) + 1. [Blocks](#blocks) + 1. [Comments](#comments) + 1. [Whitespace](#whitespace) + 1. [Commas](#commas) + 1. [Semicolons](#semicolons) + 1. [Type Casting & Coercion](#type-casting--coercion) + 1. [Naming Conventions](#naming-conventions) + 1. [Accessors](#accessors) + 1. [Constructors](#constructors) + 1. [Events](#events) + 1. [Modules](#modules) + 1. [jQuery](#jquery) + 1. [ECMAScript 5 Compatibility](#ecmascript-5-compatibility) + 1. [Testing](#testing) + 1. [Performance](#performance) + 1. [Resources](#resources) + 1. [In the Wild](#in-the-wild) + 1. [Translation](#translation) + 1. [The JavaScript Style Guide Guide](#the-javascript-style-guide-guide) + 1. [Contributors](#contributors) + 1. [License](#license) ## Types - - **Primitives**: When you access a primitive type you work directly on its value + - **Primitives**: When you access a primitive type you work directly on its value - + `string` - + `number` - + `boolean` - + `null` - + `undefined` + + `string` + + `number` + + `boolean` + + `null` + + `undefined` - ```javascript - var foo = 1, - bar = foo; + ```javascript + var foo = 1, + bar = foo; - bar = 9; + bar = 9; - console.log(foo, bar); // => 1, 9 - ``` - - **Complex**: When you access a complex type you work on a reference to its value + console.log(foo, bar); // => 1, 9 + ``` + - **Complex**: When you access a complex type you work on a reference to its value - + `object` - + `array` - + `function` + + `object` + + `array` + + `function` - ```javascript - var foo = [1, 2], - bar = foo; + ```javascript + var foo = [1, 2], + bar = foo; - bar[0] = 9; + bar[0] = 9; - console.log(foo[0], bar[0]); // => 9, 9 - ``` + console.log(foo[0], bar[0]); // => 9, 9 + ``` **[⬆ back to top](#table-of-contents)** ## Objects - - Use the literal syntax for object creation. + - Use the literal syntax for object creation. - ```javascript - // bad - var item = new Object(); + ```javascript + // bad + var item = new Object(); - // good - var item = {}; - ``` + // good + var item = {}; + ``` **[⬆ back to top](#table-of-contents)** ## Arrays - - Use the literal syntax for array creation + - Use the literal syntax for array creation - ```javascript - // bad - var items = new Array(); + ```javascript + // bad + var items = new Array(); - // good - var items = []; - ``` + // good + var items = []; + ``` - - When you need to copy an array use Array#slice. [jsPerf](http://jsperf.com/converting-arguments-to-an-array/7) + - When you need to copy an array use Array#slice. [jsPerf](http://jsperf.com/converting-arguments-to-an-array/7) - ```javascript - var len = items.length, - itemsCopy = [], - i; + ```javascript + var len = items.length, + itemsCopy = [], + i; - // bad - for (i = 0; i < len; i++) { - itemsCopy[i] = items[i]; - } + // bad + for (i = 0; i < len; i++) { + itemsCopy[i] = items[i]; + } - // good - itemsCopy = items.slice(); - ``` + // good + itemsCopy = items.slice(); + ``` - - To convert an array-like object to an array, use Array#slice. + - To convert an array-like object to an array, use Array#slice. - ```javascript - function trigger() { - var args = Array.slice.call(arguments); - ... - } - ``` + ```javascript + function trigger() { + var args = Array.slice.call(arguments); + ... + } + ``` **[⬆ back to top](#table-of-contents)** ## Strings - - Use double quotes `""` for strings + - Use double quotes `""` for strings - ```javascript - // bad - var name = 'Immanuel Kant'; + ```javascript + // bad + var name = 'Immanuel Kant'; - // good - var name = "Immanuel Kant"; + // good + var name = "Immanuel Kant"; - // bad - var fullName = 'Immanuel ' + this.lastName; + // bad + var fullName = 'Immanuel ' + this.lastName; - // good - var fullName = "Immanuel " + this.lastName; - ``` + // good + var fullName = "Immanuel " + this.lastName; + ``` **[⬆ back to top](#table-of-contents)** ## Functions - - Function expressions: - - ```javascript - // anonymous function expression - var anonymous = function() { - return true; - }; - - // named function expression - var named = function named() { - return true; - }; - - // immediately-invoked function expression (IIFE) - (function() { - console.log("You want it to be one way... but it's the other way."); - })(); - ``` - - - Never leave space between parameters/arguments and enclosing parentheses. - - ```javascript - // bad - function imbibe( drink ) { - // ...stuff... - } - - // bad - imbibe( "seltzer" ); - - // good - function imbibe(drink) { - // ...stuff... - } - - // good - imbibe("seltzer"); - ``` - - - Follow a top down flow for declaring functions. The code should read like a newspaper. - - ```javascript - // bad - function readNextPage() { - console.log("This is getting interesting..."); - } - - var Book = { - turnPage: readNextPage() - } - - // bad - function end() { - console.log("Oh no, a twist!"); - } - - function begin() { - console.log("What's going to happen next?"); - end(); - } - - function readBook() { - begin(); - } - - // good - var Book = { - turnPage: readNextPage() - } - - function readNextPage() { - console.log("This is getting interesting..."); - } - - // good - function readBook() { - begin(); - } - - function begin() { - console.log("What's going to happen next?"); - end(); - } - - function end() { - console.log("Oh no, a twist!"); - } - ``` - - - Never declare a function in a non-function block (if, while, etc). Assign the function to a variable instead. Browsers will allow you to do it, but they all interpret it differently, which is bad. - - **Note:** ECMA-262 defines a `block` as a list of statements. A function declaration is not a statement. [Read ECMA-262's note on this issue](http://www.ecma-international.org/publications/files/ECMA-ST/Ecma-262.pdf#page=97). - - ```javascript - // bad - if (currentUser) { - function test() { - console.log("Nope."); - } - } - - // good - var test; - if (currentUser) { - test = function test() { - console.log("Yup."); - }; - } - ``` - - - Never name a parameter `arguments`, this will take precedence over the `arguments` object that is given to every function scope. - - ```javascript - // bad - function nope(name, options, arguments) { - // ...stuff... - } - - // good - function yup(name, options, args) { - // ...stuff... - } - ``` + - Function expressions: + + ```javascript + // anonymous function expression + var anonymous = function() { + return true; + }; + + // named function expression + var named = function named() { + return true; + }; + + // immediately-invoked function expression (IIFE) + (function() { + console.log("You want it to be one way... but it's the other way."); + })(); + ``` + + - Never leave space between parameters/arguments and enclosing parentheses. + + ```javascript + // bad + function imbibe( drink ) { + // ...stuff... + } + + // bad + imbibe( "seltzer" ); + + // good + function imbibe(drink) { + // ...stuff... + } + + // good + imbibe("seltzer"); + ``` + + - Follow a top down flow for declaring functions. The code should read like a newspaper. + + ```javascript + // bad + function readNextPage() { + console.log("This is getting interesting..."); + } + + var Book = { + turnPage: readNextPage() + } + + // bad + function end() { + console.log("Oh no, a twist!"); + } + + function begin() { + console.log("What's going to happen next?"); + end(); + } + + function readBook() { + begin(); + } + + // good + var Book = { + turnPage: readNextPage() + } + + function readNextPage() { + console.log("This is getting interesting..."); + } + + // good + function readBook() { + begin(); + } + + function begin() { + console.log("What's going to happen next?"); + end(); + } + + function end() { + console.log("Oh no, a twist!"); + } + ``` + + - Never declare a function in a non-function block (if, while, etc). Assign the function to a variable instead. Browsers will allow you to do it, but they all interpret it differently, which is bad. + - **Note:** ECMA-262 defines a `block` as a list of statements. A function declaration is not a statement. [Read ECMA-262's note on this issue](http://www.ecma-international.org/publications/files/ECMA-ST/Ecma-262.pdf#page=97). + + ```javascript + // bad + if (currentUser) { + function test() { + console.log("Nope."); + } + } + + // good + var test; + if (currentUser) { + test = function test() { + console.log("Yup."); + }; + } + ``` + + - Never name a parameter `arguments`, this will take precedence over the `arguments` object that is given to every function scope. + + ```javascript + // bad + function nope(name, options, arguments) { + // ...stuff... + } + + // good + function yup(name, options, args) { + // ...stuff... + } + ``` **[⬆ back to top](#table-of-contents)** @@ -277,889 +277,889 @@ ## Properties - - Use dot notation when accessing properties. + - Use dot notation when accessing properties. - ```javascript - var plato = { - athenian: true, - age: 30 - }; + ```javascript + var plato = { + athenian: true, + age: 30 + }; - // bad - var isAthenian = plato["athenian"]; + // bad + var isAthenian = plato["athenian"]; - // good - var isAthenian = plato.athenian; - ``` + // good + var isAthenian = plato.athenian; + ``` - - Use subscript notation `[]` when accessing properties with a variable. + - Use subscript notation `[]` when accessing properties with a variable. - ```javascript - var plato = { - athenian: true, - age: 30 - }; + ```javascript + var plato = { + athenian: true, + age: 30 + }; - function getProp(prop) { - return plato[prop]; - } + function getProp(prop) { + return plato[prop]; + } - var isAthenian = getProp("athenian"); - ``` + var isAthenian = getProp("athenian"); + ``` **[⬆ back to top](#table-of-contents)** ## Variables - - Always use `var` to declare variables. Not doing so will result in global variables. We want to avoid polluting the global namespace. + - Always use `var` to declare variables. Not doing so will result in global variables. We want to avoid polluting the global namespace. - ```javascript - // bad - treatise = new Treatise(); + ```javascript + // bad + treatise = new Treatise(); - // good - var treatise = new Treatise(); - ``` + // good + var treatise = new Treatise(); + ``` - - Use separate `var` declarations for multiple variables and declare each variable on a new line. + - Use separate `var` declarations for multiple variables and declare each variable on a new line. - ```javascript - // bad - var books = getBooks(), - peaceful = true, - library = "Alexandria"; + ```javascript + // bad + var books = getBooks(), + peaceful = true, + library = "Alexandria"; - // good - var books = getBooks(); - var peaceful = true; - var library = "Alexandria"; - ``` + // good + var books = getBooks(); + var peaceful = true; + var library = "Alexandria"; + ``` - - Assign variables at the top of their scope. This helps avoid issues with variable declaration and assignment hoisting related issues. + - Assign variables at the top of their scope. This helps avoid issues with variable declaration and assignment hoisting related issues. - ```javascript - // bad - function() { - test(); - console.log("doing stuff.."); + ```javascript + // bad + function() { + test(); + console.log("doing stuff.."); - //..other stuff.. + //..other stuff.. - var name = getName(); + var name = getName(); - if (name === "test") { - return false; - } + if (name === "test") { + return false; + } - return name; - } + return name; + } - // good - function() { - var name = getName(); + // good + function() { + var name = getName(); - test(); - console.log("doing stuff.."); + test(); + console.log("doing stuff.."); - //..other stuff.. + //..other stuff.. - if (name === "test") { - return false; - } + if (name === "test") { + return false; + } - return name; - } + return name; + } - // bad - function() { - var name = getName(); + // bad + function() { + var name = getName(); - if (!arguments.length) { - return false; - } + if (!arguments.length) { + return false; + } - return true; - } + return true; + } - // good - function() { - if (!arguments.length) { - return false; - } + // good + function() { + if (!arguments.length) { + return false; + } - var name = getName(); + var name = getName(); - return true; - } - ``` + return true; + } + ``` **[⬆ back to top](#table-of-contents)** ## Hoisting - - Variable declarations get hoisted to the top of their scope, their assignment does not. - - ```javascript - // we know this wouldn't work (assuming there - // is no notDefined global variable) - function example() { - console.log(notDefined); // => throws a ReferenceError - } - - // creating a variable declaration after you - // reference the variable will work due to - // variable hoisting. Note: the assignment - // value of `true` is not hoisted. - function example() { - console.log(declaredButNotAssigned); // => undefined - var declaredButNotAssigned = true; - } - - // The interpreter is hoisting the variable - // declaration to the top of the scope. - // Which means our example could be rewritten as: - function example() { - var declaredButNotAssigned; - console.log(declaredButNotAssigned); // => undefined - declaredButNotAssigned = true; - } - ``` - - - Function declarations hoist their name and the function body. - - ```javascript - function example() { - read(); // logs "Human reason has the peculiar fate in one species of its cognitions..." - - function read() { - console.log("Human reason has the peculiar fate in one species of its cognitions..."); - } - } - ``` - - - For more information refer to [JavaScript Scoping & Hoisting](http://www.adequatelygood.com/2010/2/JavaScript-Scoping-and-Hoisting) by [Ben Cherry](http://www.adequatelygood.com/) + - Variable declarations get hoisted to the top of their scope, their assignment does not. + + ```javascript + // we know this wouldn't work (assuming there + // is no notDefined global variable) + function example() { + console.log(notDefined); // => throws a ReferenceError + } + + // creating a variable declaration after you + // reference the variable will work due to + // variable hoisting. Note: the assignment + // value of `true` is not hoisted. + function example() { + console.log(declaredButNotAssigned); // => undefined + var declaredButNotAssigned = true; + } + + // The interpreter is hoisting the variable + // declaration to the top of the scope. + // Which means our example could be rewritten as: + function example() { + var declaredButNotAssigned; + console.log(declaredButNotAssigned); // => undefined + declaredButNotAssigned = true; + } + ``` + + - Function declarations hoist their name and the function body. + + ```javascript + function example() { + read(); // logs "Human reason has the peculiar fate in one species of its cognitions..." + + function read() { + console.log("Human reason has the peculiar fate in one species of its cognitions..."); + } + } + ``` + + - For more information refer to [JavaScript Scoping & Hoisting](http://www.adequatelygood.com/2010/2/JavaScript-Scoping-and-Hoisting) by [Ben Cherry](http://www.adequatelygood.com/) **[⬆ back to top](#table-of-contents)** ## Conditional Expressions & Equality - - Use `===` and `!==` over `==` and `!=`. - - Conditional expressions are evaluated using coercion with the `ToBoolean` method and always follow these simple rules: - - + **Objects** evaluate to **true** - + **Undefined** evaluates to **false** - + **Null** evaluates to **false** - + **Booleans** evaluate to **the value of the boolean** - + **Numbers** evaluate to **false** if **+0, -0, or NaN**, otherwise **true** - + **Strings** evaluate to **false** if an empty string `""`, otherwise **true** - - ```javascript - if ([0]) { - // true - // An array is an object, objects evaluate to true - } - ``` - - - Use shortcuts. - - ```javascript - // bad - if (name !== "") { - // ...stuff... - } - - // good - if (name) { - // ...stuff... - } - - // bad - if (collection.length > 0) { - // ...stuff... - } - - // good - if (collection.length) { - // ...stuff... - } - ``` - - - These shortcuts should not be used when checking for the existence of a property on an object. - - ```javascript - // bad - checks truthiness of value of the property, not for the existence of the property - if (someObject.someProperty) { - // ...stuff... - } - - // good - when checking if a property exists on an object or in its prototype chain - if ("someProperty" in someObject) { - // ...stuff... - } - - // good - when checking if a property exists on an object instance - if (someObject.hasOwnProperty("someProperty")) { - // ...stuff... - } - ``` - - - For more information see [Truth Equality and JavaScript](http://javascriptweblog.wordpress.com/2011/02/07/truth-equality-and-javascript/#more-2108) by Angus Croll + - Use `===` and `!==` over `==` and `!=`. + - Conditional expressions are evaluated using coercion with the `ToBoolean` method and always follow these simple rules: + + + **Objects** evaluate to **true** + + **Undefined** evaluates to **false** + + **Null** evaluates to **false** + + **Booleans** evaluate to **the value of the boolean** + + **Numbers** evaluate to **false** if **+0, -0, or NaN**, otherwise **true** + + **Strings** evaluate to **false** if an empty string `""`, otherwise **true** + + ```javascript + if ([0]) { + // true + // An array is an object, objects evaluate to true + } + ``` + + - Use shortcuts. + + ```javascript + // bad + if (name !== "") { + // ...stuff... + } + + // good + if (name) { + // ...stuff... + } + + // bad + if (collection.length > 0) { + // ...stuff... + } + + // good + if (collection.length) { + // ...stuff... + } + ``` + + - These shortcuts should not be used when checking for the existence of a property on an object. + + ```javascript + // bad - checks truthiness of value of the property, not for the existence of the property + if (someObject.someProperty) { + // ...stuff... + } + + // good - when checking if a property exists on an object or in its prototype chain + if ("someProperty" in someObject) { + // ...stuff... + } + + // good - when checking if a property exists on an object instance + if (someObject.hasOwnProperty("someProperty")) { + // ...stuff... + } + ``` + + - For more information see [Truth Equality and JavaScript](http://javascriptweblog.wordpress.com/2011/02/07/truth-equality-and-javascript/#more-2108) by Angus Croll **[⬆ back to top](#table-of-contents)** ## Blocks - - Use braces with all multi-line blocks. + - Use braces with all multi-line blocks. - ```javascript - // bad - if (test) - return false; + ```javascript + // bad + if (test) + return false; - // good - if (test) return false; + // good + if (test) return false; - // good - if (test) { - return false; - } + // good + if (test) { + return false; + } - // bad - function() { return false; } + // bad + function() { return false; } - // good - function() { - return false; - } - ``` + // good + function() { + return false; + } + ``` **[⬆ back to top](#table-of-contents)** ## Comments - - Use `/** ... */` for multiline comments. + - Use `/** ... */` for multiline comments. - ```javascript - // bad - // make() returns a new element - // based on the passed in tag name - // - function make(tag) { + ```javascript + // bad + // make() returns a new element + // based on the passed in tag name + // + function make(tag) { - // ...stuff... + // ...stuff... - return element; - } + return element; + } - // good - /** - * make() returns a new element - * based on the passed in tag name - * - */ - function make(tag) { + // good + /** + * make() returns a new element + * based on the passed in tag name + * + */ + function make(tag) { - // ...stuff... + // ...stuff... - return element; - } - ``` + return element; + } + ``` - - Use `//` for single line comments. Place single line comments on a new line above the subject of the comment. Put an empty line before the comment. + - Use `//` for single line comments. Place single line comments on a new line above the subject of the comment. Put an empty line before the comment. - ```javascript - // bad - var active = true; // is current tab + ```javascript + // bad + var active = true; // is current tab - // good - // is current tab - var active = true; + // good + // is current tab + var active = true; - // bad - function getType() { - console.log("fetching type..."); - // set the default type to "no type" - var type = this.type || "no type"; + // bad + function getType() { + console.log("fetching type..."); + // set the default type to "no type" + var type = this.type || "no type"; - return type; - } + return type; + } - // good - function getType() { - console.log("fetching type..."); + // good + function getType() { + console.log("fetching type..."); - // set the default type to "no type" - var type = this.type || "no type"; + // set the default type to "no type" + var type = this.type || "no type"; - return type; - } - ``` + return type; + } + ``` - - Prefixing your comments with FIXME, TODO, or HACK helps other developers quickly understand what kind of problem you're pointing out. These are different than regular comments because they are actionable. FIXME indicates that a problem that still needs a solution. TODO describes the form of a solution to a problem. HACK indicates a fast, suboptimal solution that should be improved. + - Prefixing your comments with FIXME, TODO, or HACK helps other developers quickly understand what kind of problem you're pointing out. These are different than regular comments because they are actionable. FIXME indicates that a problem that still needs a solution. TODO describes the form of a solution to a problem. HACK indicates a fast, suboptimal solution that should be improved. - - Use `// FIXME:` to annotate problems + - Use `// FIXME:` to annotate problems - ```javascript - function Calculator() { + ```javascript + function Calculator() { - // FIXME: shouldn't use a global here - total = 0; + // FIXME: shouldn't use a global here + total = 0; - return this; - } - ``` + return this; + } + ``` - - Use `// TODO:` to annotate solutions to problems + - Use `// TODO:` to annotate solutions to problems - ```javascript - function Calculator() { + ```javascript + function Calculator() { - // TODO: total should be configurable by an options param - this.total = 0; + // TODO: total should be configurable by an options param + this.total = 0; - return this; - } - ``` + return this; + } + ``` **[⬆ back to top](#table-of-contents)** ## Whitespace - - Use soft tabs set to 4 spaces - - ```javascript - // bad - function() { - ∙var name; - } - - // bad - function() { - ∙∙var name; - } - - // good - function() { - ∙∙∙∙var name; - } - ``` - - - Place 1 space before the leading brace. - - ```javascript - // bad - function test(){ - console.log("test"); - } - - // good - function test() { - console.log("test"); - } - - // bad - falcon.set("attr",{ - age: "1 year", - breed: "Maltese" - }); - - // good - falcon.set("attr", { - age: "1 year", - breed: "Maltese" - }); - ``` - - - Set off operators with spaces. - - ```javascript - // bad - var x=y+5; - - // good - var x = y + 5; - ``` - - - Use indentation when making long method chains. - - ```javascript - // bad - $("#items").find(".selected").highlight().end().find(".open").updateCount(); - - // good - $("#items") - .find(".selected") - .highlight() - .end() - .find(".open") - .updateCount(); - - // bad - var leds = stage.selectAll(".led").data(data).enter().append("svg:svg").class("led", true) - .attr("width", (radius + margin) * 2).append("svg:g") - .attr("transform", "translate(" + (radius + margin) + "," + (radius + margin) + ")") - .call(tron.led); - - // good - var leds = stage.selectAll(".led") - .data(data) - .enter().append("svg:svg") - .class("led", true) - .attr("width", (radius + margin) * 2) - .append("svg:g") - .attr("transform", "translate(" + (radius + margin) + "," + (radius + margin) + ")") - .call(tron.led); - ``` + - Use soft tabs set to 4 spaces + + ```javascript + // bad + function() { + ∙var name; + } + + // bad + function() { + ∙∙var name; + } + + // good + function() { + ∙∙∙∙var name; + } + ``` + + - Place 1 space before the leading brace. + + ```javascript + // bad + function test(){ + console.log("test"); + } + + // good + function test() { + console.log("test"); + } + + // bad + falcon.set("attr",{ + age: "1 year", + breed: "Maltese" + }); + + // good + falcon.set("attr", { + age: "1 year", + breed: "Maltese" + }); + ``` + + - Set off operators with spaces. + + ```javascript + // bad + var x=y+5; + + // good + var x = y + 5; + ``` + + - Use indentation when making long method chains. + + ```javascript + // bad + $("#items").find(".selected").highlight().end().find(".open").updateCount(); + + // good + $("#items") + .find(".selected") + .highlight() + .end() + .find(".open") + .updateCount(); + + // bad + var leds = stage.selectAll(".led").data(data).enter().append("svg:svg").class("led", true) + .attr("width", (radius + margin) * 2).append("svg:g") + .attr("transform", "translate(" + (radius + margin) + "," + (radius + margin) + ")") + .call(tron.led); + + // good + var leds = stage.selectAll(".led") + .data(data) + .enter().append("svg:svg") + .class("led", true) + .attr("width", (radius + margin) * 2) + .append("svg:g") + .attr("transform", "translate(" + (radius + margin) + "," + (radius + margin) + ")") + .call(tron.led); + ``` **[⬆ back to top](#table-of-contents)** ## Commas - - Leading commas: **Nope.** - - ```javascript - // bad - var hero = { - firstName: "Immanuel" - , lastName: "Kant" - , birthPlace: "Koenigsberg" - , masterWork: "The Critique of Pure Reason" - }; - - // good - var hero = { - firstName: "Immanuel", - lastName: "Kant", - birthPlace: "Koenigsberg", - masterWork: "The Critique of Pure Reason" - }; - ``` + - Leading commas: **Nope.** + + ```javascript + // bad + var hero = { + firstName: "Immanuel" + , lastName: "Kant" + , birthPlace: "Koenigsberg" + , masterWork: "The Critique of Pure Reason" + }; + + // good + var hero = { + firstName: "Immanuel", + lastName: "Kant", + birthPlace: "Koenigsberg", + masterWork: "The Critique of Pure Reason" + }; + ``` **[⬆ back to top](#table-of-contents)** ## Semicolons - - **Yup.** - - ```javascript - // bad - (function() { - var name = "Ada" - return name - })() - - // good - (function() { - var name = "Ada"; - return name; - })(); - - // good - ;(function() { - var name = "Ada"; - return name; - })(); - ``` + - **Yup.** + + ```javascript + // bad + (function() { + var name = "Ada" + return name + })() + + // good + (function() { + var name = "Ada"; + return name; + })(); + + // good + ;(function() { + var name = "Ada"; + return name; + })(); + ``` **[⬆ back to top](#table-of-contents)** ## Type Casting & Coercion - - Perform type coercion at the beginning of the statement. - - Strings: + - Perform type coercion at the beginning of the statement. + - Strings: - ```javascript - // => this.reviewScore = 9; + ```javascript + // => this.reviewScore = 9; - // bad - var totalScore = this.reviewScore + ""; + // bad + var totalScore = this.reviewScore + ""; - // good - var totalScore = "" + this.reviewScore; + // good + var totalScore = "" + this.reviewScore; - // bad - var totalScore = "" + this.reviewScore + " total score"; + // bad + var totalScore = "" + this.reviewScore + " total score"; - // good - var totalScore = this.reviewScore + " total score"; - ``` + // good + var totalScore = this.reviewScore + " total score"; + ``` - - Use `parseInt` for Numbers and always with a radix for type casting. + - Use `parseInt` for Numbers and always with a radix for type casting. - ```javascript - var inputValue = "4"; + ```javascript + var inputValue = "4"; - // bad - var val = new Number(inputValue); + // bad + var val = new Number(inputValue); - // bad - var val = +inputValue; + // bad + var val = +inputValue; - // bad - var val = inputValue >> 0; + // bad + var val = inputValue >> 0; - // bad - var val = parseInt(inputValue); + // bad + var val = parseInt(inputValue); - // good - var val = Number(inputValue); + // good + var val = Number(inputValue); - // good - var val = parseInt(inputValue, 10); - ``` + // good + var val = parseInt(inputValue, 10); + ``` - - If for whatever reason you are doing something wild and `parseInt` is your bottleneck and need to use Bitshift for [performance reasons](http://jsperf.com/coercion-vs-casting/3), leave a comment explaining why and what you're doing. + - If for whatever reason you are doing something wild and `parseInt` is your bottleneck and need to use Bitshift for [performance reasons](http://jsperf.com/coercion-vs-casting/3), leave a comment explaining why and what you're doing. - ```javascript - // good - /** - * parseInt was the reason my code was slow. - * Bitshifting the String to coerce it to a - * Number made it a lot faster. - */ - var val = inputValue >> 0; - ``` + ```javascript + // good + /** + * parseInt was the reason my code was slow. + * Bitshifting the String to coerce it to a + * Number made it a lot faster. + */ + var val = inputValue >> 0; + ``` - - **Note:** Be careful when using bitshift operations. Numbers are represented as [64-bit values](http://es5.github.io/#x4.3.19), but Bitshift operations always return a 32-bit integer ([source](http://es5.github.io/#x11.7)). Bitshift can lead to unexpected behavior for integer values larger than 32 bits. [Discussion](https://github.com/airbnb/javascript/issues/109). Largest signed 32-bit Int is 2,147,483,647: + - **Note:** Be careful when using bitshift operations. Numbers are represented as [64-bit values](http://es5.github.io/#x4.3.19), but Bitshift operations always return a 32-bit integer ([source](http://es5.github.io/#x11.7)). Bitshift can lead to unexpected behavior for integer values larger than 32 bits. [Discussion](https://github.com/airbnb/javascript/issues/109). Largest signed 32-bit Int is 2,147,483,647: - ```javascript - 2147483647 >> 0 //=> 2147483647 - 2147483648 >> 0 //=> -2147483648 - 2147483649 >> 0 //=> -2147483647 - ``` + ```javascript + 2147483647 >> 0 //=> 2147483647 + 2147483648 >> 0 //=> -2147483648 + 2147483649 >> 0 //=> -2147483647 + ``` - - Booleans: + - Booleans: - ```javascript - var age = 0; + ```javascript + var age = 0; - // bad - var hasAge = new Boolean(age); + // bad + var hasAge = new Boolean(age); - // good - var hasAge = Boolean(age); + // good + var hasAge = Boolean(age); - // good - var hasAge = !!age; - ``` + // good + var hasAge = !!age; + ``` **[⬆ back to top](#table-of-contents)** ## Naming Conventions - - Avoid single letter names. Be descriptive with your naming. - - ```javascript - // bad - function q() { - // ...stuff... - } - - // good - function query() { - // ..stuff.. - } - ``` - - - Use camelCase when naming objects, functions, and instances - - ```javascript - // bad - var OBJEcttsssss = {}; - var this_is_my_object = {}; - function c() {} - var u = new user({ - name: "Ada Lovelace" - }); - - // good - var thisIsMyObject = {}; - function thisIsMyFunction() {} - var user = new User({ - name: "Ada Lovelace" - }); - ``` - - - Use PascalCase when naming constructors or classes - - ```javascript - // bad - function user(options) { - this.name = options.name; - } - - var bad = new user({ - name: "nope" - }); - - // good - function User(options) { - this.name = options.name; - } - - var good = new User({ - name: "yup" - }); - ``` - - - When saving a reference to `this` use `_this`. - - ```javascript - // bad - function() { - var self = this; - return function() { - console.log(self); - }; - } - - // bad - function() { - var that = this; - return function() { - console.log(that); - }; - } - - // good - function() { - var _this = this; - return function() { - console.log(_this); - }; - } - ``` - - - **Note:** IE8 and below exhibit some quirks with named function expressions. See [http://kangax.github.io/nfe/](http://kangax.github.io/nfe/) for more info. + - Avoid single letter names. Be descriptive with your naming. + + ```javascript + // bad + function q() { + // ...stuff... + } + + // good + function query() { + // ..stuff.. + } + ``` + + - Use camelCase when naming objects, functions, and instances + + ```javascript + // bad + var OBJEcttsssss = {}; + var this_is_my_object = {}; + function c() {} + var u = new user({ + name: "Ada Lovelace" + }); + + // good + var thisIsMyObject = {}; + function thisIsMyFunction() {} + var user = new User({ + name: "Ada Lovelace" + }); + ``` + + - Use PascalCase when naming constructors or classes + + ```javascript + // bad + function user(options) { + this.name = options.name; + } + + var bad = new user({ + name: "nope" + }); + + // good + function User(options) { + this.name = options.name; + } + + var good = new User({ + name: "yup" + }); + ``` + + - When saving a reference to `this` use `_this`. + + ```javascript + // bad + function() { + var self = this; + return function() { + console.log(self); + }; + } + + // bad + function() { + var that = this; + return function() { + console.log(that); + }; + } + + // good + function() { + var _this = this; + return function() { + console.log(_this); + }; + } + ``` + + - **Note:** IE8 and below exhibit some quirks with named function expressions. See [http://kangax.github.io/nfe/](http://kangax.github.io/nfe/) for more info. **[⬆ back to top](#table-of-contents)** ## Accessors - - Accessor functions on Backbone models do not use the getVal() pattern. + - Accessor functions on Backbone models do not use the getVal() pattern. - ```javascript - // bad - bowie.getAlbums(); + ```javascript + // bad + bowie.getAlbums(); - // good - bowie.albums(); - ``` + // good + bowie.albums(); + ``` - - If the property is a boolean, use isVal() or hasVal() + - If the property is a boolean, use isVal() or hasVal() - ```javascript - // bad - if (!bowie.albums()) { - return false; - } + ```javascript + // bad + if (!bowie.albums()) { + return false; + } - // good - if (!bowie.hasAlbums()) { - return false; - } - ``` + // good + if (!bowie.hasAlbums()) { + return false; + } + ``` **[⬆ back to top](#table-of-contents)** ## Constructors - - Assign methods to the prototype object, instead of overwriting the prototype with a new object. Overwriting the prototype makes inheritance impossible: by resetting the prototype you'll overwrite the base! - - ```javascript - function Writer() { - console.log("new writer"); - } - - // bad - Writer.prototype = { - procrastinate: function() { - console.log("procrastinating"); - }, - - dream: function() { - console.log("dreaming"); - } - }; - - // good - Writer.prototype.procrastinate = function() { - console.log("procrastinating"); - }; - - Writer.prototype.dream = function() { - console.log("dreaming"); - }; - ``` - - - Methods can return `this` to help with method chaining. - - ```javascript - // bad - Writer.prototype.resolve = function() { - this.madeResolution = true; - return true; - }; - - Writer.prototype.imagineMovingTo = function(destination) { - this.destination = destination; - }; - - var roommate = new Writer(); - roommate.resolve(); // => true - roommate.imagineMovingTo("Paris") // => undefined - - // good - Writer.prototype.resolve = function() { - this.madeResolution = true; - return this; - }; - - Writer.prototype.imagineMovingTo = function(destination) { - this.destination = destination; - return this; - }; - - var roommate = new Writer(); - - roommate.resolve() - .imagineMovingTo("Paris"); - ``` - - - It's okay to write a custom toString() method, just make sure it works successfully and causes no side effects. - - ```javascript - function Writer(options) { - options || (options = {}); - this.name = options.name || "no name"; - } - - Writer.prototype.getName = function getName() { - return this.name; - }; - - Writer.prototype.toString = function toString() { - return "Writer - " + this.getName(); - }; - ``` + - Assign methods to the prototype object, instead of overwriting the prototype with a new object. Overwriting the prototype makes inheritance impossible: by resetting the prototype you'll overwrite the base! + + ```javascript + function Writer() { + console.log("new writer"); + } + + // bad + Writer.prototype = { + procrastinate: function() { + console.log("procrastinating"); + }, + + dream: function() { + console.log("dreaming"); + } + }; + + // good + Writer.prototype.procrastinate = function() { + console.log("procrastinating"); + }; + + Writer.prototype.dream = function() { + console.log("dreaming"); + }; + ``` + + - Methods can return `this` to help with method chaining. + + ```javascript + // bad + Writer.prototype.resolve = function() { + this.madeResolution = true; + return true; + }; + + Writer.prototype.imagineMovingTo = function(destination) { + this.destination = destination; + }; + + var roommate = new Writer(); + roommate.resolve(); // => true + roommate.imagineMovingTo("Paris") // => undefined + + // good + Writer.prototype.resolve = function() { + this.madeResolution = true; + return this; + }; + + Writer.prototype.imagineMovingTo = function(destination) { + this.destination = destination; + return this; + }; + + var roommate = new Writer(); + + roommate.resolve() + .imagineMovingTo("Paris"); + ``` + + - It's okay to write a custom toString() method, just make sure it works successfully and causes no side effects. + + ```javascript + function Writer(options) { + options || (options = {}); + this.name = options.name || "no name"; + } + + Writer.prototype.getName = function getName() { + return this.name; + }; + + Writer.prototype.toString = function toString() { + return "Writer - " + this.getName(); + }; + ``` **[⬆ back to top](#table-of-contents)** ## Events - **[⬆ back to top](#table-of-contents)** + **[⬆ back to top](#table-of-contents)** ## Modules - - Always declare `"use strict";` at the top of the module. + - Always declare `"use strict";` at the top of the module. **[⬆ back to top](#table-of-contents)** ## jQuery - - Prefix jQuery object variables with a `$`. + - Prefix jQuery object variables with a `$`. - ```javascript - // bad - var sidebar = ".sidebar"); + ```javascript + // bad + var sidebar = ".sidebar"); - // good - var $sidebar = ".sidebar"); - ``` + // good + var $sidebar = ".sidebar"); + ``` - - Cache jQuery lookups. + - Cache jQuery lookups. - ```javascript - // bad - function setSidebar() { - ".sidebar").hide(); + ```javascript + // bad + function setSidebar() { + ".sidebar").hide(); - // ...stuff... + // ...stuff... - ".sidebar").css({ - "background-color": "pink" - }); - } + ".sidebar").css({ + "background-color": "pink" + }); + } - // good - function setSidebar() { - var $sidebar = ".sidebar"); - $sidebar.hide(); + // good + function setSidebar() { + var $sidebar = ".sidebar"); + $sidebar.hide(); - // ...stuff... + // ...stuff... - $sidebar.css({ - "background-color": "pink" - }); - } - ``` + $sidebar.css({ + "background-color": "pink" + }); + } + ``` - - Scope jQuery object queries to Backbone view using this.$el.find() + - Scope jQuery object queries to Backbone view using this.$el.find() - ```javascript - // bad - $("ul", ".sidebar").hide(); + ```javascript + // bad + $("ul", ".sidebar").hide(); - // bad - $(".sidebar").find("ul").hide(); + // bad + $(".sidebar").find("ul").hide(); - // good - this.$el.find(".sidebar ul").hide(); + // good + this.$el.find(".sidebar ul").hide(); - // good - this.$el.find(".sidebar > ul").hide(); + // good + this.$el.find(".sidebar > ul").hide(); - // good - $sidebar.find("ul").hide(); - ``` + // good + $sidebar.find("ul").hide(); + ``` **[⬆ back to top](#table-of-contents)** ## ECMAScript 5 Compatibility - - Refer to [Kangax](https://twitter.com/kangax/)'s ES5 [compatibility table](http://kangax.github.com/es5-compat-table/) + - Refer to [Kangax](https://twitter.com/kangax/)'s ES5 [compatibility table](http://kangax.github.com/es5-compat-table/) **[⬆ back to top](#table-of-contents)** ## Testing - - **Yup.** + - **Yup.** - ```javascript - function() { - return true; - } - ``` + ```javascript + function() { + return true; + } + ``` **[⬆ back to top](#table-of-contents)** ## Performance - - [On Layout & Web Performance](http://kellegous.com/j/2013/01/26/layout-performance/) - - [String vs Array Concat](http://jsperf.com/string-vs-array-concat/2) - - [Try/Catch Cost In a Loop](http://jsperf.com/try-catch-in-loop-cost) - - [Bang Function](http://jsperf.com/bang-function) - - [jQuery Find vs Context, Selector](http://jsperf.com/jquery-find-vs-context-sel/13) - - [innerHTML vs textContent for script text](http://jsperf.com/innerhtml-vs-textcontent-for-script-text) - - [Long String Concatenation](http://jsperf.com/ya-string-concat) - - Loading... + - [On Layout & Web Performance](http://kellegous.com/j/2013/01/26/layout-performance/) + - [String vs Array Concat](http://jsperf.com/string-vs-array-concat/2) + - [Try/Catch Cost In a Loop](http://jsperf.com/try-catch-in-loop-cost) + - [Bang Function](http://jsperf.com/bang-function) + - [jQuery Find vs Context, Selector](http://jsperf.com/jquery-find-vs-context-sel/13) + - [innerHTML vs textContent for script text](http://jsperf.com/innerhtml-vs-textcontent-for-script-text) + - [Long String Concatenation](http://jsperf.com/ya-string-concat) + - Loading... **[⬆ back to top](#table-of-contents)** @@ -1169,99 +1169,99 @@ **Read This** - - [Annotated ECMAScript 5.1](http://es5.github.com/) + - [Annotated ECMAScript 5.1](http://es5.github.com/) **Other Styleguides** - - [Google JavaScript Style Guide](http://google-styleguide.googlecode.com/svn/trunk/javascriptguide.xml) - - [jQuery Core Style Guidelines](http://docs.jquery.com/JQuery_Core_Style_Guidelines) - - [Principles of Writing Consistent, Idiomatic JavaScript](https://github.com/rwldrn/idiomatic.js/) + - [Google JavaScript Style Guide](http://google-styleguide.googlecode.com/svn/trunk/javascriptguide.xml) + - [jQuery Core Style Guidelines](http://docs.jquery.com/JQuery_Core_Style_Guidelines) + - [Principles of Writing Consistent, Idiomatic JavaScript](https://github.com/rwldrn/idiomatic.js/) **Other Styles** - - [Naming this in nested functions](https://gist.github.com/4135065) - Christian Johansen - - [Conditional Callbacks](https://github.com/airbnb/javascript/issues/52) - - [Popular JavaScript Coding Conventions on Github](http://sideeffect.kr/popularconvention/#javascript) + - [Naming this in nested functions](https://gist.github.com/4135065) - Christian Johansen + - [Conditional Callbacks](https://github.com/airbnb/javascript/issues/52) + - [Popular JavaScript Coding Conventions on Github](http://sideeffect.kr/popularconvention/#javascript) **Further Reading** - - [Understanding JavaScript Closures](http://javascriptweblog.wordpress.com/2010/10/25/understanding-javascript-closures/) - Angus Croll - - [Basic JavaScript for the impatient programmer](http://www.2ality.com/2013/06/basic-javascript.html) - Dr. Axel Rauschmayer - - [You Might Not Need jQuery](http://youmightnotneedjquery.com/) - Zack Bloom & Adam Schwartz - - [ES6 Features](https://github.com/lukehoban/es6features) - Luke Hoban + - [Understanding JavaScript Closures](http://javascriptweblog.wordpress.com/2010/10/25/understanding-javascript-closures/) - Angus Croll + - [Basic JavaScript for the impatient programmer](http://www.2ality.com/2013/06/basic-javascript.html) - Dr. Axel Rauschmayer + - [You Might Not Need jQuery](http://youmightnotneedjquery.com/) - Zack Bloom & Adam Schwartz + - [ES6 Features](https://github.com/lukehoban/es6features) - Luke Hoban **Books** - - [JavaScript: The Good Parts](http://www.amazon.com/JavaScript-Good-Parts-Douglas-Crockford/dp/0596517742) - Douglas Crockford - - [JavaScript Patterns](http://www.amazon.com/JavaScript-Patterns-Stoyan-Stefanov/dp/0596806752) - Stoyan Stefanov - - [Pro JavaScript Design Patterns](http://www.amazon.com/JavaScript-Design-Patterns-Recipes-Problem-Solution/dp/159059908X) - Ross Harmes and Dustin Diaz - - [High Performance Web Sites: Essential Knowledge for Front-End Engineers](http://www.amazon.com/High-Performance-Web-Sites-Essential/dp/0596529309) - Steve Souders - - [Maintainable JavaScript](http://www.amazon.com/Maintainable-JavaScript-Nicholas-C-Zakas/dp/1449327680) - Nicholas C. Zakas - - [JavaScript Web Applications](http://www.amazon.com/JavaScript-Web-Applications-Alex-MacCaw/dp/144930351X) - Alex MacCaw - - [Pro JavaScript Techniques](http://www.amazon.com/Pro-JavaScript-Techniques-John-Resig/dp/1590597273) - John Resig - - [Smashing Node.js: JavaScript Everywhere](http://www.amazon.com/Smashing-Node-js-JavaScript-Everywhere-Magazine/dp/1119962595) - Guillermo Rauch - - [Secrets of the JavaScript Ninja](http://www.amazon.com/Secrets-JavaScript-Ninja-John-Resig/dp/193398869X) - John Resig and Bear Bibeault - - [Human JavaScript](http://humanjavascript.com/) - Henrik Joreteg - - [Superhero.js](http://superherojs.com/) - Kim Joar Bekkelund, Mads Mobæk, & Olav Bjorkoy - - [JSBooks](http://jsbooks.revolunet.com/) - - [Third Party JavaScript](http://manning.com/vinegar/) - Ben Vinegar and Anton Kovalyov + - [JavaScript: The Good Parts](http://www.amazon.com/JavaScript-Good-Parts-Douglas-Crockford/dp/0596517742) - Douglas Crockford + - [JavaScript Patterns](http://www.amazon.com/JavaScript-Patterns-Stoyan-Stefanov/dp/0596806752) - Stoyan Stefanov + - [Pro JavaScript Design Patterns](http://www.amazon.com/JavaScript-Design-Patterns-Recipes-Problem-Solution/dp/159059908X) - Ross Harmes and Dustin Diaz + - [High Performance Web Sites: Essential Knowledge for Front-End Engineers](http://www.amazon.com/High-Performance-Web-Sites-Essential/dp/0596529309) - Steve Souders + - [Maintainable JavaScript](http://www.amazon.com/Maintainable-JavaScript-Nicholas-C-Zakas/dp/1449327680) - Nicholas C. Zakas + - [JavaScript Web Applications](http://www.amazon.com/JavaScript-Web-Applications-Alex-MacCaw/dp/144930351X) - Alex MacCaw + - [Pro JavaScript Techniques](http://www.amazon.com/Pro-JavaScript-Techniques-John-Resig/dp/1590597273) - John Resig + - [Smashing Node.js: JavaScript Everywhere](http://www.amazon.com/Smashing-Node-js-JavaScript-Everywhere-Magazine/dp/1119962595) - Guillermo Rauch + - [Secrets of the JavaScript Ninja](http://www.amazon.com/Secrets-JavaScript-Ninja-John-Resig/dp/193398869X) - John Resig and Bear Bibeault + - [Human JavaScript](http://humanjavascript.com/) - Henrik Joreteg + - [Superhero.js](http://superherojs.com/) - Kim Joar Bekkelund, Mads Mobæk, & Olav Bjorkoy + - [JSBooks](http://jsbooks.revolunet.com/) + - [Third Party JavaScript](http://manning.com/vinegar/) - Ben Vinegar and Anton Kovalyov **Blogs** - - [DailyJS](http://dailyjs.com/) - - [JavaScript Weekly](http://javascriptweekly.com/) - - [JavaScript, JavaScript...](http://javascriptweblog.wordpress.com/) - - [Bocoup Weblog](http://weblog.bocoup.com/) - - [Adequately Good](http://www.adequatelygood.com/) - - [NCZOnline](http://www.nczonline.net/) - - [Perfection Kills](http://perfectionkills.com/) - - [Ben Alman](http://benalman.com/) - - [Dmitry Baranovskiy](http://dmitry.baranovskiy.com/) - - [Dustin Diaz](http://dustindiaz.com/) - - [nettuts](http://net.tutsplus.com/?s=javascript) + - [DailyJS](http://dailyjs.com/) + - [JavaScript Weekly](http://javascriptweekly.com/) + - [JavaScript, JavaScript...](http://javascriptweblog.wordpress.com/) + - [Bocoup Weblog](http://weblog.bocoup.com/) + - [Adequately Good](http://www.adequatelygood.com/) + - [NCZOnline](http://www.nczonline.net/) + - [Perfection Kills](http://perfectionkills.com/) + - [Ben Alman](http://benalman.com/) + - [Dmitry Baranovskiy](http://dmitry.baranovskiy.com/) + - [Dustin Diaz](http://dustindiaz.com/) + - [nettuts](http://net.tutsplus.com/?s=javascript) **[⬆ back to top](#table-of-contents)** ## In the Wild - This is a list of organizations that are using variations of the Airbnb style guide. - - - **Aan Zee**: [AanZee/javascript](https://github.com/AanZee/javascript) - - **Airbnb**: [airbnb/javascript](https://github.com/airbnb/javascript) - - **American Insitutes for Research**: [AIRAST/javascript](https://github.com/AIRAST/javascript) - - **Compass Learning**: [compasslearning/javascript-style-guide](https://github.com/compasslearning/javascript-style-guide) - - **Digitpaint** [digitpaint/javascript](https://github.com/digitpaint/javascript) - - **ExactTarget**: [ExactTarget/javascript](https://github.com/ExactTarget/javascript) - - **Gawker Media**: [gawkermedia/javascript](https://github.com/gawkermedia/javascript) - - **GeneralElectric**: [GeneralElectric/javascript](https://github.com/GeneralElectric/javascript) - - **GoodData**: [gooddata/gdc-js-style](https://github.com/gooddata/gdc-js-style) - - **Grooveshark**: [grooveshark/javascript](https://github.com/grooveshark/javascript) - - **How About We**: [howaboutwe/javascript](https://github.com/howaboutwe/javascript) - - **Mighty Spring**: [mightyspring/javascript](https://github.com/mightyspring/javascript) - - **MinnPost**: [MinnPost/javascript](https://github.com/MinnPost/javascript) - - **ModCloth**: [modcloth/javascript](https://github.com/modcloth/javascript) - - **Money Advice Service**: [moneyadviceservice/javascript](https://github.com/moneyadviceservice/javascript) - - **National Geographic**: [natgeo/javascript](https://github.com/natgeo/javascript) - - **National Park Service**: [nationalparkservice/javascript](https://github.com/nationalparkservice/javascript) - - **Orion Health**: [orionhealth/javascript](https://github.com/orionhealth/javascript) - - **Peerby**: [Peerby/javascript](https://github.com/Peerby/javascript) - - **Razorfish**: [razorfish/javascript-style-guide](https://github.com/razorfish/javascript-style-guide) - - **SeekingAlpha**: [seekingalpha/javascript-style-guide](https://github.com/seekingalpha/javascript-style-guide) - - **reddit**: [reddit/styleguide/javascript](https://github.com/reddit/styleguide/tree/master/javascript) - - **REI**: [reidev/js-style-guide](https://github.com/reidev/js-style-guide) - - **Ripple**: [ripple/javascript-style-guide](https://github.com/ripple/javascript-style-guide) - - **Shutterfly**: [shutterfly/javascript](https://github.com/shutterfly/javascript) - - **Userify**: [userify/javascript](https://github.com/userify/javascript) - - **Zillow**: [zillow/javascript](https://github.com/zillow/javascript) - - **ZocDoc**: [ZocDoc/javascript](https://github.com/ZocDoc/javascript) + This is a list of organizations that are using variations of the Airbnb style guide. + + - **Aan Zee**: [AanZee/javascript](https://github.com/AanZee/javascript) + - **Airbnb**: [airbnb/javascript](https://github.com/airbnb/javascript) + - **American Insitutes for Research**: [AIRAST/javascript](https://github.com/AIRAST/javascript) + - **Compass Learning**: [compasslearning/javascript-style-guide](https://github.com/compasslearning/javascript-style-guide) + - **Digitpaint** [digitpaint/javascript](https://github.com/digitpaint/javascript) + - **ExactTarget**: [ExactTarget/javascript](https://github.com/ExactTarget/javascript) + - **Gawker Media**: [gawkermedia/javascript](https://github.com/gawkermedia/javascript) + - **GeneralElectric**: [GeneralElectric/javascript](https://github.com/GeneralElectric/javascript) + - **GoodData**: [gooddata/gdc-js-style](https://github.com/gooddata/gdc-js-style) + - **Grooveshark**: [grooveshark/javascript](https://github.com/grooveshark/javascript) + - **How About We**: [howaboutwe/javascript](https://github.com/howaboutwe/javascript) + - **Mighty Spring**: [mightyspring/javascript](https://github.com/mightyspring/javascript) + - **MinnPost**: [MinnPost/javascript](https://github.com/MinnPost/javascript) + - **ModCloth**: [modcloth/javascript](https://github.com/modcloth/javascript) + - **Money Advice Service**: [moneyadviceservice/javascript](https://github.com/moneyadviceservice/javascript) + - **National Geographic**: [natgeo/javascript](https://github.com/natgeo/javascript) + - **National Park Service**: [nationalparkservice/javascript](https://github.com/nationalparkservice/javascript) + - **Orion Health**: [orionhealth/javascript](https://github.com/orionhealth/javascript) + - **Peerby**: [Peerby/javascript](https://github.com/Peerby/javascript) + - **Razorfish**: [razorfish/javascript-style-guide](https://github.com/razorfish/javascript-style-guide) + - **SeekingAlpha**: [seekingalpha/javascript-style-guide](https://github.com/seekingalpha/javascript-style-guide) + - **reddit**: [reddit/styleguide/javascript](https://github.com/reddit/styleguide/tree/master/javascript) + - **REI**: [reidev/js-style-guide](https://github.com/reidev/js-style-guide) + - **Ripple**: [ripple/javascript-style-guide](https://github.com/ripple/javascript-style-guide) + - **Shutterfly**: [shutterfly/javascript](https://github.com/shutterfly/javascript) + - **Userify**: [userify/javascript](https://github.com/userify/javascript) + - **Zillow**: [zillow/javascript](https://github.com/zillow/javascript) + - **ZocDoc**: [ZocDoc/javascript](https://github.com/ZocDoc/javascript) ## The JavaScript Style Guide Guide - - [Reference](https://github.com/airbnb/javascript/wiki/The-JavaScript-Style-Guide-Guide) + - [Reference](https://github.com/airbnb/javascript/wiki/The-JavaScript-Style-Guide-Guide) ## Contributors - - [View Contributors](https://github.com/airbnb/javascript/graphs/contributors) + - [View Contributors](https://github.com/airbnb/javascript/graphs/contributors) ## License From 8622ee26391d1a4a44e0206db57e8db1b1dfcf1f Mon Sep 17 00:00:00 2001 From: John Mumm Date: Sat, 14 Jun 2014 11:22:00 -0400 Subject: [PATCH 15/19] Fix indentation --- README.md | 1920 ++++++++++++++++++++++++++--------------------------- 1 file changed, 960 insertions(+), 960 deletions(-) diff --git a/README.md b/README.md index 1b6af23f02..d0f9fd3d65 100644 --- a/README.md +++ b/README.md @@ -5,271 +5,271 @@ ## Table of Contents - 1. [Types](#types) - 1. [Objects](#objects) - 1. [Arrays](#arrays) - 1. [Strings](#strings) - 1. [Functions](#functions) - 1. [Properties](#properties) - 1. [Variables](#variables) - 1. [Hoisting](#hoisting) - 1. [Conditional Expressions & Equality](#conditional-expressions--equality) - 1. [Blocks](#blocks) - 1. [Comments](#comments) - 1. [Whitespace](#whitespace) - 1. [Commas](#commas) - 1. [Semicolons](#semicolons) - 1. [Type Casting & Coercion](#type-casting--coercion) - 1. [Naming Conventions](#naming-conventions) - 1. [Accessors](#accessors) - 1. [Constructors](#constructors) - 1. [Events](#events) - 1. [Modules](#modules) - 1. [jQuery](#jquery) - 1. [ECMAScript 5 Compatibility](#ecmascript-5-compatibility) - 1. [Testing](#testing) - 1. [Performance](#performance) - 1. [Resources](#resources) - 1. [In the Wild](#in-the-wild) - 1. [Translation](#translation) - 1. [The JavaScript Style Guide Guide](#the-javascript-style-guide-guide) - 1. [Contributors](#contributors) - 1. [License](#license) +1. [Types](#types) +1. [Objects](#objects) +1. [Arrays](#arrays) +1. [Strings](#strings) +1. [Functions](#functions) +1. [Properties](#properties) +1. [Variables](#variables) +1. [Hoisting](#hoisting) +1. [Conditional Expressions & Equality](#conditional-expressions--equality) +1. [Blocks](#blocks) +1. [Comments](#comments) +1. [Whitespace](#whitespace) +1. [Commas](#commas) +1. [Semicolons](#semicolons) +1. [Type Casting & Coercion](#type-casting--coercion) +1. [Naming Conventions](#naming-conventions) +1. [Accessors](#accessors) +1. [Constructors](#constructors) +1. [Events](#events) +1. [Modules](#modules) +1. [jQuery](#jquery) +1. [ECMAScript 5 Compatibility](#ecmascript-5-compatibility) +1. [Testing](#testing) +1. [Performance](#performance) +1. [Resources](#resources) +1. [In the Wild](#in-the-wild) +1. [Translation](#translation) +1. [The JavaScript Style Guide Guide](#the-javascript-style-guide-guide) +1. [Contributors](#contributors) +1. [License](#license) ## Types - - **Primitives**: When you access a primitive type you work directly on its value +- **Primitives**: When you access a primitive type you work directly on its value - + `string` - + `number` - + `boolean` - + `null` - + `undefined` + + `string` + + `number` + + `boolean` + + `null` + + `undefined` - ```javascript - var foo = 1, - bar = foo; + ```javascript + var foo = 1, + bar = foo; - bar = 9; + bar = 9; - console.log(foo, bar); // => 1, 9 - ``` - - **Complex**: When you access a complex type you work on a reference to its value + console.log(foo, bar); // => 1, 9 + ``` +- **Complex**: When you access a complex type you work on a reference to its value - + `object` - + `array` - + `function` + + `object` + + `array` + + `function` - ```javascript - var foo = [1, 2], - bar = foo; + ```javascript + var foo = [1, 2], + bar = foo; - bar[0] = 9; + bar[0] = 9; - console.log(foo[0], bar[0]); // => 9, 9 - ``` + console.log(foo[0], bar[0]); // => 9, 9 + ``` **[⬆ back to top](#table-of-contents)** ## Objects - - Use the literal syntax for object creation. +- Use the literal syntax for object creation. - ```javascript - // bad - var item = new Object(); + ```javascript + // bad + var item = new Object(); - // good - var item = {}; - ``` + // good + var item = {}; + ``` **[⬆ back to top](#table-of-contents)** ## Arrays - - Use the literal syntax for array creation +- Use the literal syntax for array creation - ```javascript - // bad - var items = new Array(); + ```javascript + // bad + var items = new Array(); - // good - var items = []; - ``` + // good + var items = []; + ``` - - When you need to copy an array use Array#slice. [jsPerf](http://jsperf.com/converting-arguments-to-an-array/7) +- When you need to copy an array use Array#slice. [jsPerf](http://jsperf.com/converting-arguments-to-an-array/7) - ```javascript - var len = items.length, - itemsCopy = [], - i; + ```javascript + var len = items.length, + itemsCopy = [], + i; - // bad - for (i = 0; i < len; i++) { - itemsCopy[i] = items[i]; - } + // bad + for (i = 0; i < len; i++) { + itemsCopy[i] = items[i]; + } - // good - itemsCopy = items.slice(); - ``` + // good + itemsCopy = items.slice(); + ``` - - To convert an array-like object to an array, use Array#slice. +- To convert an array-like object to an array, use Array#slice. - ```javascript - function trigger() { - var args = Array.slice.call(arguments); - ... - } - ``` + ```javascript + function trigger() { + var args = Array.slice.call(arguments); + ... + } + ``` **[⬆ back to top](#table-of-contents)** ## Strings - - Use double quotes `""` for strings +- Use double quotes `""` for strings - ```javascript - // bad - var name = 'Immanuel Kant'; + ```javascript + // bad + var name = 'Immanuel Kant'; - // good - var name = "Immanuel Kant"; + // good + var name = "Immanuel Kant"; - // bad - var fullName = 'Immanuel ' + this.lastName; + // bad + var fullName = 'Immanuel ' + this.lastName; - // good - var fullName = "Immanuel " + this.lastName; - ``` + // good + var fullName = "Immanuel " + this.lastName; + ``` **[⬆ back to top](#table-of-contents)** ## Functions - - Function expressions: - - ```javascript - // anonymous function expression - var anonymous = function() { - return true; - }; - - // named function expression - var named = function named() { - return true; - }; - - // immediately-invoked function expression (IIFE) - (function() { - console.log("You want it to be one way... but it's the other way."); - })(); - ``` - - - Never leave space between parameters/arguments and enclosing parentheses. - - ```javascript - // bad - function imbibe( drink ) { - // ...stuff... - } - - // bad - imbibe( "seltzer" ); - - // good - function imbibe(drink) { - // ...stuff... - } - - // good - imbibe("seltzer"); - ``` - - - Follow a top down flow for declaring functions. The code should read like a newspaper. - - ```javascript - // bad - function readNextPage() { - console.log("This is getting interesting..."); - } - - var Book = { - turnPage: readNextPage() - } - - // bad - function end() { - console.log("Oh no, a twist!"); - } - - function begin() { - console.log("What's going to happen next?"); - end(); - } - - function readBook() { - begin(); - } - - // good - var Book = { - turnPage: readNextPage() - } - - function readNextPage() { - console.log("This is getting interesting..."); - } - - // good - function readBook() { - begin(); - } - - function begin() { - console.log("What's going to happen next?"); - end(); - } - - function end() { - console.log("Oh no, a twist!"); - } - ``` - - - Never declare a function in a non-function block (if, while, etc). Assign the function to a variable instead. Browsers will allow you to do it, but they all interpret it differently, which is bad. - - **Note:** ECMA-262 defines a `block` as a list of statements. A function declaration is not a statement. [Read ECMA-262's note on this issue](http://www.ecma-international.org/publications/files/ECMA-ST/Ecma-262.pdf#page=97). - - ```javascript - // bad - if (currentUser) { - function test() { - console.log("Nope."); - } - } - - // good - var test; - if (currentUser) { - test = function test() { - console.log("Yup."); - }; - } - ``` - - - Never name a parameter `arguments`, this will take precedence over the `arguments` object that is given to every function scope. - - ```javascript - // bad - function nope(name, options, arguments) { - // ...stuff... - } - - // good - function yup(name, options, args) { - // ...stuff... - } - ``` +- Function expressions: + + ```javascript + // anonymous function expression + var anonymous = function() { + return true; + }; + + // named function expression + var named = function named() { + return true; + }; + + // immediately-invoked function expression (IIFE) + (function() { + console.log("You want it to be one way... but it's the other way."); + })(); + ``` + +- Never leave space between parameters/arguments and enclosing parentheses. + + ```javascript + // bad + function imbibe( drink ) { + // ...stuff... + } + + // bad + imbibe( "seltzer" ); + + // good + function imbibe(drink) { + // ...stuff... + } + + // good + imbibe("seltzer"); + ``` + +- Follow a top down flow for declaring functions. The code should read like a newspaper. + + ```javascript + // bad + function readNextPage() { + console.log("This is getting interesting..."); + } + + var Book = { + turnPage: readNextPage() + } + + // bad + function end() { + console.log("Oh no, a twist!"); + } + + function begin() { + console.log("What's going to happen next?"); + end(); + } + + function readBook() { + begin(); + } + + // good + var Book = { + turnPage: readNextPage() + } + + function readNextPage() { + console.log("This is getting interesting..."); + } + + // good + function readBook() { + begin(); + } + + function begin() { + console.log("What's going to happen next?"); + end(); + } + + function end() { + console.log("Oh no, a twist!"); + } + ``` + +- Never declare a function in a non-function block (if, while, etc). Assign the function to a variable instead. Browsers will allow you to do it, but they all interpret it differently, which is bad. +- **Note:** ECMA-262 defines a `block` as a list of statements. A function declaration is not a statement. [Read ECMA-262's note on this issue](http://www.ecma-international.org/publications/files/ECMA-ST/Ecma-262.pdf#page=97). + + ```javascript + // bad + if (currentUser) { + function test() { + console.log("Nope."); + } + } + + // good + var test; + if (currentUser) { + test = function test() { + console.log("Yup."); + }; + } + ``` + +- Never name a parameter `arguments`, this will take precedence over the `arguments` object that is given to every function scope. + + ```javascript + // bad + function nope(name, options, arguments) { + // ...stuff... + } + + // good + function yup(name, options, args) { + // ...stuff... + } + ``` **[⬆ back to top](#table-of-contents)** @@ -277,889 +277,889 @@ ## Properties - - Use dot notation when accessing properties. +- Use dot notation when accessing properties. - ```javascript - var plato = { - athenian: true, - age: 30 - }; + ```javascript + var plato = { + athenian: true, + age: 30 + }; - // bad - var isAthenian = plato["athenian"]; + // bad + var isAthenian = plato["athenian"]; - // good - var isAthenian = plato.athenian; - ``` + // good + var isAthenian = plato.athenian; + ``` - - Use subscript notation `[]` when accessing properties with a variable. +- Use subscript notation `[]` when accessing properties with a variable. - ```javascript - var plato = { - athenian: true, - age: 30 - }; + ```javascript + var plato = { + athenian: true, + age: 30 + }; - function getProp(prop) { - return plato[prop]; - } + function getProp(prop) { + return plato[prop]; + } - var isAthenian = getProp("athenian"); - ``` + var isAthenian = getProp("athenian"); + ``` **[⬆ back to top](#table-of-contents)** ## Variables - - Always use `var` to declare variables. Not doing so will result in global variables. We want to avoid polluting the global namespace. +- Always use `var` to declare variables. Not doing so will result in global variables. We want to avoid polluting the global namespace. - ```javascript - // bad - treatise = new Treatise(); + ```javascript + // bad + treatise = new Treatise(); - // good - var treatise = new Treatise(); - ``` + // good + var treatise = new Treatise(); + ``` - - Use separate `var` declarations for multiple variables and declare each variable on a new line. +- Use separate `var` declarations for multiple variables and declare each variable on a new line. - ```javascript - // bad - var books = getBooks(), - peaceful = true, - library = "Alexandria"; + ```javascript + // bad + var books = getBooks(), + peaceful = true, + library = "Alexandria"; - // good - var books = getBooks(); - var peaceful = true; - var library = "Alexandria"; - ``` + // good + var books = getBooks(); + var peaceful = true; + var library = "Alexandria"; + ``` - - Assign variables at the top of their scope. This helps avoid issues with variable declaration and assignment hoisting related issues. +- Assign variables at the top of their scope. This helps avoid issues with variable declaration and assignment hoisting related issues. - ```javascript - // bad - function() { - test(); - console.log("doing stuff.."); + ```javascript + // bad + function() { + test(); + console.log("doing stuff.."); - //..other stuff.. + //..other stuff.. - var name = getName(); + var name = getName(); - if (name === "test") { - return false; - } + if (name === "test") { + return false; + } - return name; - } + return name; + } - // good - function() { - var name = getName(); + // good + function() { + var name = getName(); - test(); - console.log("doing stuff.."); + test(); + console.log("doing stuff.."); - //..other stuff.. + //..other stuff.. - if (name === "test") { - return false; - } + if (name === "test") { + return false; + } - return name; - } + return name; + } - // bad - function() { - var name = getName(); + // bad + function() { + var name = getName(); - if (!arguments.length) { - return false; - } + if (!arguments.length) { + return false; + } - return true; - } + return true; + } - // good - function() { - if (!arguments.length) { - return false; - } + // good + function() { + if (!arguments.length) { + return false; + } - var name = getName(); + var name = getName(); - return true; - } - ``` + return true; + } + ``` **[⬆ back to top](#table-of-contents)** ## Hoisting - - Variable declarations get hoisted to the top of their scope, their assignment does not. - - ```javascript - // we know this wouldn't work (assuming there - // is no notDefined global variable) - function example() { - console.log(notDefined); // => throws a ReferenceError - } - - // creating a variable declaration after you - // reference the variable will work due to - // variable hoisting. Note: the assignment - // value of `true` is not hoisted. - function example() { - console.log(declaredButNotAssigned); // => undefined - var declaredButNotAssigned = true; - } - - // The interpreter is hoisting the variable - // declaration to the top of the scope. - // Which means our example could be rewritten as: - function example() { - var declaredButNotAssigned; - console.log(declaredButNotAssigned); // => undefined - declaredButNotAssigned = true; - } - ``` - - - Function declarations hoist their name and the function body. - - ```javascript - function example() { - read(); // logs "Human reason has the peculiar fate in one species of its cognitions..." - - function read() { - console.log("Human reason has the peculiar fate in one species of its cognitions..."); - } - } - ``` - - - For more information refer to [JavaScript Scoping & Hoisting](http://www.adequatelygood.com/2010/2/JavaScript-Scoping-and-Hoisting) by [Ben Cherry](http://www.adequatelygood.com/) +- Variable declarations get hoisted to the top of their scope, their assignment does not. + + ```javascript + // we know this wouldn't work (assuming there + // is no notDefined global variable) + function example() { + console.log(notDefined); // => throws a ReferenceError + } + + // creating a variable declaration after you + // reference the variable will work due to + // variable hoisting. Note: the assignment + // value of `true` is not hoisted. + function example() { + console.log(declaredButNotAssigned); // => undefined + var declaredButNotAssigned = true; + } + + // The interpreter is hoisting the variable + // declaration to the top of the scope. + // Which means our example could be rewritten as: + function example() { + var declaredButNotAssigned; + console.log(declaredButNotAssigned); // => undefined + declaredButNotAssigned = true; + } + ``` + +- Function declarations hoist their name and the function body. + + ```javascript + function example() { + read(); // logs "Human reason has the peculiar fate in one species of its cognitions..." + + function read() { + console.log("Human reason has the peculiar fate in one species of its cognitions..."); + } + } + ``` + +- For more information refer to [JavaScript Scoping & Hoisting](http://www.adequatelygood.com/2010/2/JavaScript-Scoping-and-Hoisting) by [Ben Cherry](http://www.adequatelygood.com/) **[⬆ back to top](#table-of-contents)** ## Conditional Expressions & Equality - - Use `===` and `!==` over `==` and `!=`. - - Conditional expressions are evaluated using coercion with the `ToBoolean` method and always follow these simple rules: - - + **Objects** evaluate to **true** - + **Undefined** evaluates to **false** - + **Null** evaluates to **false** - + **Booleans** evaluate to **the value of the boolean** - + **Numbers** evaluate to **false** if **+0, -0, or NaN**, otherwise **true** - + **Strings** evaluate to **false** if an empty string `""`, otherwise **true** - - ```javascript - if ([0]) { - // true - // An array is an object, objects evaluate to true - } - ``` - - - Use shortcuts. - - ```javascript - // bad - if (name !== "") { - // ...stuff... - } - - // good - if (name) { - // ...stuff... - } - - // bad - if (collection.length > 0) { - // ...stuff... - } - - // good - if (collection.length) { - // ...stuff... - } - ``` - - - These shortcuts should not be used when checking for the existence of a property on an object. - - ```javascript - // bad - checks truthiness of value of the property, not for the existence of the property - if (someObject.someProperty) { - // ...stuff... - } - - // good - when checking if a property exists on an object or in its prototype chain - if ("someProperty" in someObject) { - // ...stuff... - } - - // good - when checking if a property exists on an object instance - if (someObject.hasOwnProperty("someProperty")) { - // ...stuff... - } - ``` - - - For more information see [Truth Equality and JavaScript](http://javascriptweblog.wordpress.com/2011/02/07/truth-equality-and-javascript/#more-2108) by Angus Croll +- Use `===` and `!==` over `==` and `!=`. +- Conditional expressions are evaluated using coercion with the `ToBoolean` method and always follow these simple rules: + + + **Objects** evaluate to **true** + + **Undefined** evaluates to **false** + + **Null** evaluates to **false** + + **Booleans** evaluate to **the value of the boolean** + + **Numbers** evaluate to **false** if **+0, -0, or NaN**, otherwise **true** + + **Strings** evaluate to **false** if an empty string `""`, otherwise **true** + + ```javascript + if ([0]) { + // true + // An array is an object, objects evaluate to true + } + ``` + +- Use shortcuts. + + ```javascript + // bad + if (name !== "") { + // ...stuff... + } + + // good + if (name) { + // ...stuff... + } + + // bad + if (collection.length > 0) { + // ...stuff... + } + + // good + if (collection.length) { + // ...stuff... + } + ``` + +- These shortcuts should not be used when checking for the existence of a property on an object. + + ```javascript + // bad - checks truthiness of value of the property, not for the existence of the property + if (someObject.someProperty) { + // ...stuff... + } + + // good - when checking if a property exists on an object or in its prototype chain + if ("someProperty" in someObject) { + // ...stuff... + } + + // good - when checking if a property exists on an object instance + if (someObject.hasOwnProperty("someProperty")) { + // ...stuff... + } + ``` + +- For more information see [Truth Equality and JavaScript](http://javascriptweblog.wordpress.com/2011/02/07/truth-equality-and-javascript/#more-2108) by Angus Croll **[⬆ back to top](#table-of-contents)** ## Blocks - - Use braces with all multi-line blocks. +- Use braces with all multi-line blocks. - ```javascript - // bad - if (test) - return false; + ```javascript + // bad + if (test) + return false; - // good - if (test) return false; + // good + if (test) return false; - // good - if (test) { - return false; - } + // good + if (test) { + return false; + } - // bad - function() { return false; } + // bad + function() { return false; } - // good - function() { - return false; - } - ``` + // good + function() { + return false; + } + ``` **[⬆ back to top](#table-of-contents)** ## Comments - - Use `/** ... */` for multiline comments. +- Use `/** ... */` for multiline comments. - ```javascript - // bad - // make() returns a new element - // based on the passed in tag name - // - function make(tag) { + ```javascript + // bad + // make() returns a new element + // based on the passed in tag name + // + function make(tag) { - // ...stuff... + // ...stuff... - return element; - } + return element; + } - // good - /** - * make() returns a new element - * based on the passed in tag name - * - */ - function make(tag) { + // good + /** + * make() returns a new element + * based on the passed in tag name + * + */ + function make(tag) { - // ...stuff... + // ...stuff... - return element; - } - ``` + return element; + } + ``` - - Use `//` for single line comments. Place single line comments on a new line above the subject of the comment. Put an empty line before the comment. +- Use `//` for single line comments. Place single line comments on a new line above the subject of the comment. Put an empty line before the comment. - ```javascript - // bad - var active = true; // is current tab + ```javascript + // bad + var active = true; // is current tab - // good - // is current tab - var active = true; + // good + // is current tab + var active = true; - // bad - function getType() { - console.log("fetching type..."); - // set the default type to "no type" - var type = this.type || "no type"; + // bad + function getType() { + console.log("fetching type..."); + // set the default type to "no type" + var type = this.type || "no type"; - return type; - } + return type; + } - // good - function getType() { - console.log("fetching type..."); + // good + function getType() { + console.log("fetching type..."); - // set the default type to "no type" - var type = this.type || "no type"; + // set the default type to "no type" + var type = this.type || "no type"; - return type; - } - ``` + return type; + } + ``` - - Prefixing your comments with FIXME, TODO, or HACK helps other developers quickly understand what kind of problem you're pointing out. These are different than regular comments because they are actionable. FIXME indicates that a problem that still needs a solution. TODO describes the form of a solution to a problem. HACK indicates a fast, suboptimal solution that should be improved. +- Prefixing your comments with FIXME, TODO, or HACK helps other developers quickly understand what kind of problem you're pointing out. These are different than regular comments because they are actionable. FIXME indicates that a problem that still needs a solution. TODO describes the form of a solution to a problem. HACK indicates a fast, suboptimal solution that should be improved. - - Use `// FIXME:` to annotate problems +- Use `// FIXME:` to annotate problems - ```javascript - function Calculator() { + ```javascript + function Calculator() { - // FIXME: shouldn't use a global here - total = 0; + // FIXME: shouldn't use a global here + total = 0; - return this; - } - ``` + return this; + } + ``` - - Use `// TODO:` to annotate solutions to problems +- Use `// TODO:` to annotate solutions to problems - ```javascript - function Calculator() { + ```javascript + function Calculator() { - // TODO: total should be configurable by an options param - this.total = 0; + // TODO: total should be configurable by an options param + this.total = 0; - return this; - } - ``` + return this; + } +``` **[⬆ back to top](#table-of-contents)** ## Whitespace - - Use soft tabs set to 4 spaces - - ```javascript - // bad - function() { - ∙var name; - } - - // bad - function() { - ∙∙var name; - } - - // good - function() { - ∙∙∙∙var name; - } - ``` - - - Place 1 space before the leading brace. - - ```javascript - // bad - function test(){ - console.log("test"); - } - - // good - function test() { - console.log("test"); - } - - // bad - falcon.set("attr",{ - age: "1 year", - breed: "Maltese" - }); - - // good - falcon.set("attr", { - age: "1 year", - breed: "Maltese" - }); - ``` - - - Set off operators with spaces. - - ```javascript - // bad - var x=y+5; - - // good - var x = y + 5; - ``` - - - Use indentation when making long method chains. - - ```javascript - // bad - $("#items").find(".selected").highlight().end().find(".open").updateCount(); - - // good - $("#items") - .find(".selected") - .highlight() - .end() - .find(".open") - .updateCount(); - - // bad - var leds = stage.selectAll(".led").data(data).enter().append("svg:svg").class("led", true) - .attr("width", (radius + margin) * 2).append("svg:g") - .attr("transform", "translate(" + (radius + margin) + "," + (radius + margin) + ")") - .call(tron.led); - - // good - var leds = stage.selectAll(".led") - .data(data) - .enter().append("svg:svg") - .class("led", true) - .attr("width", (radius + margin) * 2) - .append("svg:g") - .attr("transform", "translate(" + (radius + margin) + "," + (radius + margin) + ")") - .call(tron.led); - ``` +- Use soft tabs set to 4 spaces + + ```javascript + // bad + function() { + ∙var name; + } + + // bad + function() { + ∙∙var name; + } + + // good + function() { + ∙∙∙∙var name; + } + ``` + +- Place 1 space before the leading brace. + + ```javascript + // bad + function test(){ + console.log("test"); + } + + // good + function test() { + console.log("test"); + } + + // bad + falcon.set("attr",{ + age: "1 year", + breed: "Maltese" + }); + + // good + falcon.set("attr", { + age: "1 year", + breed: "Maltese" + }); + ``` + +- Set off operators with spaces. + + ```javascript + // bad + var x=y+5; + + // good + var x = y + 5; + ``` + +- Use indentation when making long method chains. + + ```javascript + // bad + $("#items").find(".selected").highlight().end().find(".open").updateCount(); + + // good + $("#items") + .find(".selected") + .highlight() + .end() + .find(".open") + .updateCount(); + + // bad + var leds = stage.selectAll(".led").data(data).enter().append("svg:svg").class("led", true) + .attr("width", (radius + margin) * 2).append("svg:g") + .attr("transform", "translate(" + (radius + margin) + "," + (radius + margin) + ")") + .call(tron.led); + + // good + var leds = stage.selectAll(".led") + .data(data) + .enter().append("svg:svg") + .class("led", true) + .attr("width", (radius + margin) * 2) + .append("svg:g") + .attr("transform", "translate(" + (radius + margin) + "," + (radius + margin) + ")") + .call(tron.led); + ``` **[⬆ back to top](#table-of-contents)** ## Commas - - Leading commas: **Nope.** - - ```javascript - // bad - var hero = { - firstName: "Immanuel" - , lastName: "Kant" - , birthPlace: "Koenigsberg" - , masterWork: "The Critique of Pure Reason" - }; - - // good - var hero = { - firstName: "Immanuel", - lastName: "Kant", - birthPlace: "Koenigsberg", - masterWork: "The Critique of Pure Reason" - }; - ``` +- Leading commas: **Nope.** + + ```javascript + // bad + var hero = { + firstName: "Immanuel" + , lastName: "Kant" + , birthPlace: "Koenigsberg" + , masterWork: "The Critique of Pure Reason" + }; + + // good + var hero = { + firstName: "Immanuel", + lastName: "Kant", + birthPlace: "Koenigsberg", + masterWork: "The Critique of Pure Reason" + }; + ``` **[⬆ back to top](#table-of-contents)** ## Semicolons - - **Yup.** +- **Yup.** - ```javascript - // bad - (function() { - var name = "Ada" - return name - })() + ```javascript + // bad + (function() { + var name = "Ada" + return name + })() - // good - (function() { - var name = "Ada"; - return name; - })(); + // good + (function() { + var name = "Ada"; + return name; + })(); - // good - ;(function() { - var name = "Ada"; - return name; - })(); - ``` + // good + ;(function() { + var name = "Ada"; + return name; + })(); + ``` **[⬆ back to top](#table-of-contents)** ## Type Casting & Coercion - - Perform type coercion at the beginning of the statement. - - Strings: +- Perform type coercion at the beginning of the statement. +- Strings: - ```javascript - // => this.reviewScore = 9; + ```javascript + // => this.reviewScore = 9; - // bad - var totalScore = this.reviewScore + ""; + // bad + var totalScore = this.reviewScore + ""; - // good - var totalScore = "" + this.reviewScore; + // good + var totalScore = "" + this.reviewScore; - // bad - var totalScore = "" + this.reviewScore + " total score"; + // bad + var totalScore = "" + this.reviewScore + " total score"; - // good - var totalScore = this.reviewScore + " total score"; - ``` + // good + var totalScore = this.reviewScore + " total score"; + ``` - - Use `parseInt` for Numbers and always with a radix for type casting. +- Use `parseInt` for Numbers and always with a radix for type casting. - ```javascript - var inputValue = "4"; + ```javascript + var inputValue = "4"; - // bad - var val = new Number(inputValue); + // bad + var val = new Number(inputValue); - // bad - var val = +inputValue; + // bad + var val = +inputValue; - // bad - var val = inputValue >> 0; + // bad + var val = inputValue >> 0; - // bad - var val = parseInt(inputValue); + // bad + var val = parseInt(inputValue); - // good - var val = Number(inputValue); + // good + var val = Number(inputValue); - // good - var val = parseInt(inputValue, 10); - ``` + // good + var val = parseInt(inputValue, 10); + ``` - - If for whatever reason you are doing something wild and `parseInt` is your bottleneck and need to use Bitshift for [performance reasons](http://jsperf.com/coercion-vs-casting/3), leave a comment explaining why and what you're doing. +- If for whatever reason you are doing something wild and `parseInt` is your bottleneck and need to use Bitshift for [performance reasons](http://jsperf.com/coercion-vs-casting/3), leave a comment explaining why and what you're doing. - ```javascript - // good - /** - * parseInt was the reason my code was slow. - * Bitshifting the String to coerce it to a - * Number made it a lot faster. - */ - var val = inputValue >> 0; - ``` + ```javascript + // good + /** + * parseInt was the reason my code was slow. + * Bitshifting the String to coerce it to a + * Number made it a lot faster. + */ + var val = inputValue >> 0; + ``` - - **Note:** Be careful when using bitshift operations. Numbers are represented as [64-bit values](http://es5.github.io/#x4.3.19), but Bitshift operations always return a 32-bit integer ([source](http://es5.github.io/#x11.7)). Bitshift can lead to unexpected behavior for integer values larger than 32 bits. [Discussion](https://github.com/airbnb/javascript/issues/109). Largest signed 32-bit Int is 2,147,483,647: +- **Note:** Be careful when using bitshift operations. Numbers are represented as [64-bit values](http://es5.github.io/#x4.3.19), but Bitshift operations always return a 32-bit integer ([source](http://es5.github.io/#x11.7)). Bitshift can lead to unexpected behavior for integer values larger than 32 bits. [Discussion](https://github.com/airbnb/javascript/issues/109). Largest signed 32-bit Int is 2,147,483,647: - ```javascript - 2147483647 >> 0 //=> 2147483647 - 2147483648 >> 0 //=> -2147483648 - 2147483649 >> 0 //=> -2147483647 - ``` + ```javascript + 2147483647 >> 0 //=> 2147483647 + 2147483648 >> 0 //=> -2147483648 + 2147483649 >> 0 //=> -2147483647 + ``` - - Booleans: +- Booleans: - ```javascript - var age = 0; + ```javascript + var age = 0; - // bad - var hasAge = new Boolean(age); + // bad + var hasAge = new Boolean(age); - // good - var hasAge = Boolean(age); + // good + var hasAge = Boolean(age); - // good - var hasAge = !!age; - ``` + // good + var hasAge = !!age; + ``` **[⬆ back to top](#table-of-contents)** ## Naming Conventions - - Avoid single letter names. Be descriptive with your naming. - - ```javascript - // bad - function q() { - // ...stuff... - } - - // good - function query() { - // ..stuff.. - } - ``` - - - Use camelCase when naming objects, functions, and instances - - ```javascript - // bad - var OBJEcttsssss = {}; - var this_is_my_object = {}; - function c() {} - var u = new user({ - name: "Ada Lovelace" - }); - - // good - var thisIsMyObject = {}; - function thisIsMyFunction() {} - var user = new User({ - name: "Ada Lovelace" - }); - ``` - - - Use PascalCase when naming constructors or classes - - ```javascript - // bad - function user(options) { - this.name = options.name; - } - - var bad = new user({ - name: "nope" - }); - - // good - function User(options) { - this.name = options.name; - } - - var good = new User({ - name: "yup" - }); - ``` - - - When saving a reference to `this` use `_this`. - - ```javascript - // bad - function() { - var self = this; - return function() { - console.log(self); - }; - } - - // bad - function() { - var that = this; - return function() { - console.log(that); - }; - } - - // good - function() { - var _this = this; - return function() { - console.log(_this); - }; - } - ``` - - - **Note:** IE8 and below exhibit some quirks with named function expressions. See [http://kangax.github.io/nfe/](http://kangax.github.io/nfe/) for more info. +- Avoid single letter names. Be descriptive with your naming. + + ```javascript + // bad + function q() { + // ...stuff... + } + + // good + function query() { + // ..stuff.. + } + ``` + +- Use camelCase when naming objects, functions, and instances + + ```javascript + // bad + var OBJEcttsssss = {}; + var this_is_my_object = {}; + function c() {} + var u = new user({ + name: "Ada Lovelace" + }); + + // good + var thisIsMyObject = {}; + function thisIsMyFunction() {} + var user = new User({ + name: "Ada Lovelace" + }); + ``` + +- Use PascalCase when naming constructors or classes + + ```javascript + // bad + function user(options) { + this.name = options.name; + } + + var bad = new user({ + name: "nope" + }); + + // good + function User(options) { + this.name = options.name; + } + + var good = new User({ + name: "yup" + }); + ``` + +- When saving a reference to `this` use `_this`. + + ```javascript + // bad + function() { + var self = this; + return function() { + console.log(self); + }; + } + + // bad + function() { + var that = this; + return function() { + console.log(that); + }; + } + + // good + function() { + var _this = this; + return function() { + console.log(_this); + }; + } + ``` + +- **Note:** IE8 and below exhibit some quirks with named function expressions. See [http://kangax.github.io/nfe/](http://kangax.github.io/nfe/) for more info. **[⬆ back to top](#table-of-contents)** ## Accessors - - Accessor functions on Backbone models do not use the getVal() pattern. +- Accessor functions on Backbone models do not use the getVal() pattern. - ```javascript - // bad - bowie.getAlbums(); + ```javascript + // bad + bowie.getAlbums(); - // good - bowie.albums(); - ``` + // good + bowie.albums(); + ``` - - If the property is a boolean, use isVal() or hasVal() +- If the property is a boolean, use isVal() or hasVal() - ```javascript - // bad - if (!bowie.albums()) { - return false; - } + ```javascript + // bad + if (!bowie.albums()) { + return false; + } - // good - if (!bowie.hasAlbums()) { - return false; - } - ``` + // good + if (!bowie.hasAlbums()) { + return false; + } + ``` **[⬆ back to top](#table-of-contents)** ## Constructors - - Assign methods to the prototype object, instead of overwriting the prototype with a new object. Overwriting the prototype makes inheritance impossible: by resetting the prototype you'll overwrite the base! - - ```javascript - function Writer() { - console.log("new writer"); - } - - // bad - Writer.prototype = { - procrastinate: function() { - console.log("procrastinating"); - }, - - dream: function() { - console.log("dreaming"); - } - }; - - // good - Writer.prototype.procrastinate = function() { - console.log("procrastinating"); - }; - - Writer.prototype.dream = function() { - console.log("dreaming"); - }; - ``` - - - Methods can return `this` to help with method chaining. - - ```javascript - // bad - Writer.prototype.resolve = function() { - this.madeResolution = true; - return true; - }; - - Writer.prototype.imagineMovingTo = function(destination) { - this.destination = destination; - }; - - var roommate = new Writer(); - roommate.resolve(); // => true - roommate.imagineMovingTo("Paris") // => undefined - - // good - Writer.prototype.resolve = function() { - this.madeResolution = true; - return this; - }; - - Writer.prototype.imagineMovingTo = function(destination) { - this.destination = destination; - return this; - }; - - var roommate = new Writer(); - - roommate.resolve() - .imagineMovingTo("Paris"); - ``` - - - It's okay to write a custom toString() method, just make sure it works successfully and causes no side effects. - - ```javascript - function Writer(options) { - options || (options = {}); - this.name = options.name || "no name"; - } - - Writer.prototype.getName = function getName() { - return this.name; - }; - - Writer.prototype.toString = function toString() { - return "Writer - " + this.getName(); - }; - ``` +- Assign methods to the prototype object, instead of overwriting the prototype with a new object. Overwriting the prototype makes inheritance impossible: by resetting the prototype you'll overwrite the base! + + ```javascript + function Writer() { + console.log("new writer"); + } + + // bad + Writer.prototype = { + procrastinate: function() { + console.log("procrastinating"); + }, + + dream: function() { + console.log("dreaming"); + } + }; + + // good + Writer.prototype.procrastinate = function() { + console.log("procrastinating"); + }; + + Writer.prototype.dream = function() { + console.log("dreaming"); + }; + ``` + +- Methods can return `this` to help with method chaining. + + ```javascript + // bad + Writer.prototype.resolve = function() { + this.madeResolution = true; + return true; + }; + + Writer.prototype.imagineMovingTo = function(destination) { + this.destination = destination; + }; + + var roommate = new Writer(); + roommate.resolve(); // => true + roommate.imagineMovingTo("Paris") // => undefined + + // good + Writer.prototype.resolve = function() { + this.madeResolution = true; + return this; + }; + + Writer.prototype.imagineMovingTo = function(destination) { + this.destination = destination; + return this; + }; + + var roommate = new Writer(); + + roommate.resolve() + .imagineMovingTo("Paris"); + ``` + +- It's okay to write a custom toString() method, just make sure it works successfully and causes no side effects. + + ```javascript + function Writer(options) { + options || (options = {}); + this.name = options.name || "no name"; + } + + Writer.prototype.getName = function getName() { + return this.name; + }; + + Writer.prototype.toString = function toString() { + return "Writer - " + this.getName(); + }; + ``` **[⬆ back to top](#table-of-contents)** ## Events - **[⬆ back to top](#table-of-contents)** +**[⬆ back to top](#table-of-contents)** ## Modules - - Always declare `"use strict";` at the top of the module. +- Always declare `"use strict";` at the top of the module. **[⬆ back to top](#table-of-contents)** ## jQuery - - Prefix jQuery object variables with a `$`. +- Prefix jQuery object variables with a `$`. - ```javascript - // bad - var sidebar = ".sidebar"); + ```javascript + // bad + var sidebar = ".sidebar"); - // good - var $sidebar = ".sidebar"); - ``` + // good + var $sidebar = ".sidebar"); + ``` - - Cache jQuery lookups. +- Cache jQuery lookups. - ```javascript - // bad - function setSidebar() { - ".sidebar").hide(); + ```javascript + // bad + function setSidebar() { + ".sidebar").hide(); - // ...stuff... + // ...stuff... - ".sidebar").css({ - "background-color": "pink" - }); - } + ".sidebar").css({ + "background-color": "pink" + }); + } - // good - function setSidebar() { - var $sidebar = ".sidebar"); - $sidebar.hide(); + // good + function setSidebar() { + var $sidebar = ".sidebar"); + $sidebar.hide(); - // ...stuff... + // ...stuff... - $sidebar.css({ - "background-color": "pink" - }); - } - ``` + $sidebar.css({ + "background-color": "pink" + }); + } + ``` - - Scope jQuery object queries to Backbone view using this.$el.find() +- Scope jQuery object queries to Backbone view using this.$el.find() - ```javascript - // bad - $("ul", ".sidebar").hide(); + ```javascript + // bad + $("ul", ".sidebar").hide(); - // bad - $(".sidebar").find("ul").hide(); + // bad + $(".sidebar").find("ul").hide(); - // good - this.$el.find(".sidebar ul").hide(); + // good + this.$el.find(".sidebar ul").hide(); - // good - this.$el.find(".sidebar > ul").hide(); + // good + this.$el.find(".sidebar > ul").hide(); - // good - $sidebar.find("ul").hide(); - ``` + // good + $sidebar.find("ul").hide(); + ``` **[⬆ back to top](#table-of-contents)** ## ECMAScript 5 Compatibility - - Refer to [Kangax](https://twitter.com/kangax/)'s ES5 [compatibility table](http://kangax.github.com/es5-compat-table/) +- Refer to [Kangax](https://twitter.com/kangax/)'s ES5 [compatibility table](http://kangax.github.com/es5-compat-table/) **[⬆ back to top](#table-of-contents)** ## Testing - - **Yup.** +- **Yup.** - ```javascript - function() { - return true; - } - ``` + ```javascript + function() { + return true; + } + ``` **[⬆ back to top](#table-of-contents)** ## Performance - - [On Layout & Web Performance](http://kellegous.com/j/2013/01/26/layout-performance/) - - [String vs Array Concat](http://jsperf.com/string-vs-array-concat/2) - - [Try/Catch Cost In a Loop](http://jsperf.com/try-catch-in-loop-cost) - - [Bang Function](http://jsperf.com/bang-function) - - [jQuery Find vs Context, Selector](http://jsperf.com/jquery-find-vs-context-sel/13) - - [innerHTML vs textContent for script text](http://jsperf.com/innerhtml-vs-textcontent-for-script-text) - - [Long String Concatenation](http://jsperf.com/ya-string-concat) - - Loading... +- [On Layout & Web Performance](http://kellegous.com/j/2013/01/26/layout-performance/) +- [String vs Array Concat](http://jsperf.com/string-vs-array-concat/2) +- [Try/Catch Cost In a Loop](http://jsperf.com/try-catch-in-loop-cost) +- [Bang Function](http://jsperf.com/bang-function) +- [jQuery Find vs Context, Selector](http://jsperf.com/jquery-find-vs-context-sel/13) +- [innerHTML vs textContent for script text](http://jsperf.com/innerhtml-vs-textcontent-for-script-text) +- [Long String Concatenation](http://jsperf.com/ya-string-concat) +- Loading... **[⬆ back to top](#table-of-contents)** @@ -1169,99 +1169,99 @@ **Read This** - - [Annotated ECMAScript 5.1](http://es5.github.com/) +- [Annotated ECMAScript 5.1](http://es5.github.com/) **Other Styleguides** - - [Google JavaScript Style Guide](http://google-styleguide.googlecode.com/svn/trunk/javascriptguide.xml) - - [jQuery Core Style Guidelines](http://docs.jquery.com/JQuery_Core_Style_Guidelines) - - [Principles of Writing Consistent, Idiomatic JavaScript](https://github.com/rwldrn/idiomatic.js/) +- [Google JavaScript Style Guide](http://google-styleguide.googlecode.com/svn/trunk/javascriptguide.xml) +- [jQuery Core Style Guidelines](http://docs.jquery.com/JQuery_Core_Style_Guidelines) +- [Principles of Writing Consistent, Idiomatic JavaScript](https://github.com/rwldrn/idiomatic.js/) **Other Styles** - - [Naming this in nested functions](https://gist.github.com/4135065) - Christian Johansen - - [Conditional Callbacks](https://github.com/airbnb/javascript/issues/52) - - [Popular JavaScript Coding Conventions on Github](http://sideeffect.kr/popularconvention/#javascript) +- [Naming this in nested functions](https://gist.github.com/4135065) - Christian Johansen +- [Conditional Callbacks](https://github.com/airbnb/javascript/issues/52) +- [Popular JavaScript Coding Conventions on Github](http://sideeffect.kr/popularconvention/#javascript) **Further Reading** - - [Understanding JavaScript Closures](http://javascriptweblog.wordpress.com/2010/10/25/understanding-javascript-closures/) - Angus Croll - - [Basic JavaScript for the impatient programmer](http://www.2ality.com/2013/06/basic-javascript.html) - Dr. Axel Rauschmayer - - [You Might Not Need jQuery](http://youmightnotneedjquery.com/) - Zack Bloom & Adam Schwartz - - [ES6 Features](https://github.com/lukehoban/es6features) - Luke Hoban +- [Understanding JavaScript Closures](http://javascriptweblog.wordpress.com/2010/10/25/understanding-javascript-closures/) - Angus Croll +- [Basic JavaScript for the impatient programmer](http://www.2ality.com/2013/06/basic-javascript.html) - Dr. Axel Rauschmayer +- [You Might Not Need jQuery](http://youmightnotneedjquery.com/) - Zack Bloom & Adam Schwartz +- [ES6 Features](https://github.com/lukehoban/es6features) - Luke Hoban **Books** - - [JavaScript: The Good Parts](http://www.amazon.com/JavaScript-Good-Parts-Douglas-Crockford/dp/0596517742) - Douglas Crockford - - [JavaScript Patterns](http://www.amazon.com/JavaScript-Patterns-Stoyan-Stefanov/dp/0596806752) - Stoyan Stefanov - - [Pro JavaScript Design Patterns](http://www.amazon.com/JavaScript-Design-Patterns-Recipes-Problem-Solution/dp/159059908X) - Ross Harmes and Dustin Diaz - - [High Performance Web Sites: Essential Knowledge for Front-End Engineers](http://www.amazon.com/High-Performance-Web-Sites-Essential/dp/0596529309) - Steve Souders - - [Maintainable JavaScript](http://www.amazon.com/Maintainable-JavaScript-Nicholas-C-Zakas/dp/1449327680) - Nicholas C. Zakas - - [JavaScript Web Applications](http://www.amazon.com/JavaScript-Web-Applications-Alex-MacCaw/dp/144930351X) - Alex MacCaw - - [Pro JavaScript Techniques](http://www.amazon.com/Pro-JavaScript-Techniques-John-Resig/dp/1590597273) - John Resig - - [Smashing Node.js: JavaScript Everywhere](http://www.amazon.com/Smashing-Node-js-JavaScript-Everywhere-Magazine/dp/1119962595) - Guillermo Rauch - - [Secrets of the JavaScript Ninja](http://www.amazon.com/Secrets-JavaScript-Ninja-John-Resig/dp/193398869X) - John Resig and Bear Bibeault - - [Human JavaScript](http://humanjavascript.com/) - Henrik Joreteg - - [Superhero.js](http://superherojs.com/) - Kim Joar Bekkelund, Mads Mobæk, & Olav Bjorkoy - - [JSBooks](http://jsbooks.revolunet.com/) - - [Third Party JavaScript](http://manning.com/vinegar/) - Ben Vinegar and Anton Kovalyov +- [JavaScript: The Good Parts](http://www.amazon.com/JavaScript-Good-Parts-Douglas-Crockford/dp/0596517742) - Douglas Crockford +- [JavaScript Patterns](http://www.amazon.com/JavaScript-Patterns-Stoyan-Stefanov/dp/0596806752) - Stoyan Stefanov +- [Pro JavaScript Design Patterns](http://www.amazon.com/JavaScript-Design-Patterns-Recipes-Problem-Solution/dp/159059908X) - Ross Harmes and Dustin Diaz +- [High Performance Web Sites: Essential Knowledge for Front-End Engineers](http://www.amazon.com/High-Performance-Web-Sites-Essential/dp/0596529309) - Steve Souders +- [Maintainable JavaScript](http://www.amazon.com/Maintainable-JavaScript-Nicholas-C-Zakas/dp/1449327680) - Nicholas C. Zakas +- [JavaScript Web Applications](http://www.amazon.com/JavaScript-Web-Applications-Alex-MacCaw/dp/144930351X) - Alex MacCaw +- [Pro JavaScript Techniques](http://www.amazon.com/Pro-JavaScript-Techniques-John-Resig/dp/1590597273) - John Resig +- [Smashing Node.js: JavaScript Everywhere](http://www.amazon.com/Smashing-Node-js-JavaScript-Everywhere-Magazine/dp/1119962595) - Guillermo Rauch +- [Secrets of the JavaScript Ninja](http://www.amazon.com/Secrets-JavaScript-Ninja-John-Resig/dp/193398869X) - John Resig and Bear Bibeault +- [Human JavaScript](http://humanjavascript.com/) - Henrik Joreteg +- [Superhero.js](http://superherojs.com/) - Kim Joar Bekkelund, Mads Mobæk, & Olav Bjorkoy +- [JSBooks](http://jsbooks.revolunet.com/) +- [Third Party JavaScript](http://manning.com/vinegar/) - Ben Vinegar and Anton Kovalyov **Blogs** - - [DailyJS](http://dailyjs.com/) - - [JavaScript Weekly](http://javascriptweekly.com/) - - [JavaScript, JavaScript...](http://javascriptweblog.wordpress.com/) - - [Bocoup Weblog](http://weblog.bocoup.com/) - - [Adequately Good](http://www.adequatelygood.com/) - - [NCZOnline](http://www.nczonline.net/) - - [Perfection Kills](http://perfectionkills.com/) - - [Ben Alman](http://benalman.com/) - - [Dmitry Baranovskiy](http://dmitry.baranovskiy.com/) - - [Dustin Diaz](http://dustindiaz.com/) - - [nettuts](http://net.tutsplus.com/?s=javascript) +- [DailyJS](http://dailyjs.com/) +- [JavaScript Weekly](http://javascriptweekly.com/) +- [JavaScript, JavaScript...](http://javascriptweblog.wordpress.com/) +- [Bocoup Weblog](http://weblog.bocoup.com/) +- [Adequately Good](http://www.adequatelygood.com/) +- [NCZOnline](http://www.nczonline.net/) +- [Perfection Kills](http://perfectionkills.com/) +- [Ben Alman](http://benalman.com/) +- [Dmitry Baranovskiy](http://dmitry.baranovskiy.com/) +- [Dustin Diaz](http://dustindiaz.com/) +- [nettuts](http://net.tutsplus.com/?s=javascript) **[⬆ back to top](#table-of-contents)** ## In the Wild - This is a list of organizations that are using variations of the Airbnb style guide. - - - **Aan Zee**: [AanZee/javascript](https://github.com/AanZee/javascript) - - **Airbnb**: [airbnb/javascript](https://github.com/airbnb/javascript) - - **American Insitutes for Research**: [AIRAST/javascript](https://github.com/AIRAST/javascript) - - **Compass Learning**: [compasslearning/javascript-style-guide](https://github.com/compasslearning/javascript-style-guide) - - **Digitpaint** [digitpaint/javascript](https://github.com/digitpaint/javascript) - - **ExactTarget**: [ExactTarget/javascript](https://github.com/ExactTarget/javascript) - - **Gawker Media**: [gawkermedia/javascript](https://github.com/gawkermedia/javascript) - - **GeneralElectric**: [GeneralElectric/javascript](https://github.com/GeneralElectric/javascript) - - **GoodData**: [gooddata/gdc-js-style](https://github.com/gooddata/gdc-js-style) - - **Grooveshark**: [grooveshark/javascript](https://github.com/grooveshark/javascript) - - **How About We**: [howaboutwe/javascript](https://github.com/howaboutwe/javascript) - - **Mighty Spring**: [mightyspring/javascript](https://github.com/mightyspring/javascript) - - **MinnPost**: [MinnPost/javascript](https://github.com/MinnPost/javascript) - - **ModCloth**: [modcloth/javascript](https://github.com/modcloth/javascript) - - **Money Advice Service**: [moneyadviceservice/javascript](https://github.com/moneyadviceservice/javascript) - - **National Geographic**: [natgeo/javascript](https://github.com/natgeo/javascript) - - **National Park Service**: [nationalparkservice/javascript](https://github.com/nationalparkservice/javascript) - - **Orion Health**: [orionhealth/javascript](https://github.com/orionhealth/javascript) - - **Peerby**: [Peerby/javascript](https://github.com/Peerby/javascript) - - **Razorfish**: [razorfish/javascript-style-guide](https://github.com/razorfish/javascript-style-guide) - - **SeekingAlpha**: [seekingalpha/javascript-style-guide](https://github.com/seekingalpha/javascript-style-guide) - - **reddit**: [reddit/styleguide/javascript](https://github.com/reddit/styleguide/tree/master/javascript) - - **REI**: [reidev/js-style-guide](https://github.com/reidev/js-style-guide) - - **Ripple**: [ripple/javascript-style-guide](https://github.com/ripple/javascript-style-guide) - - **Shutterfly**: [shutterfly/javascript](https://github.com/shutterfly/javascript) - - **Userify**: [userify/javascript](https://github.com/userify/javascript) - - **Zillow**: [zillow/javascript](https://github.com/zillow/javascript) - - **ZocDoc**: [ZocDoc/javascript](https://github.com/ZocDoc/javascript) +This is a list of organizations that are using variations of the Airbnb style guide. + +- **Aan Zee**: [AanZee/javascript](https://github.com/AanZee/javascript) +- **Airbnb**: [airbnb/javascript](https://github.com/airbnb/javascript) +- **American Insitutes for Research**: [AIRAST/javascript](https://github.com/AIRAST/javascript) +- **Compass Learning**: [compasslearning/javascript-style-guide](https://github.com/compasslearning/javascript-style-guide) +- **Digitpaint** [digitpaint/javascript](https://github.com/digitpaint/javascript) +- **ExactTarget**: [ExactTarget/javascript](https://github.com/ExactTarget/javascript) +- **Gawker Media**: [gawkermedia/javascript](https://github.com/gawkermedia/javascript) +- **GeneralElectric**: [GeneralElectric/javascript](https://github.com/GeneralElectric/javascript) +- **GoodData**: [gooddata/gdc-js-style](https://github.com/gooddata/gdc-js-style) +- **Grooveshark**: [grooveshark/javascript](https://github.com/grooveshark/javascript) +- **How About We**: [howaboutwe/javascript](https://github.com/howaboutwe/javascript) +- **Mighty Spring**: [mightyspring/javascript](https://github.com/mightyspring/javascript) +- **MinnPost**: [MinnPost/javascript](https://github.com/MinnPost/javascript) +- **ModCloth**: [modcloth/javascript](https://github.com/modcloth/javascript) +- **Money Advice Service**: [moneyadviceservice/javascript](https://github.com/moneyadviceservice/javascript) +- **National Geographic**: [natgeo/javascript](https://github.com/natgeo/javascript) +- **National Park Service**: [nationalparkservice/javascript](https://github.com/nationalparkservice/javascript) +- **Orion Health**: [orionhealth/javascript](https://github.com/orionhealth/javascript) +- **Peerby**: [Peerby/javascript](https://github.com/Peerby/javascript) +- **Razorfish**: [razorfish/javascript-style-guide](https://github.com/razorfish/javascript-style-guide) +- **SeekingAlpha**: [seekingalpha/javascript-style-guide](https://github.com/seekingalpha/javascript-style-guide) +- **reddit**: [reddit/styleguide/javascript](https://github.com/reddit/styleguide/tree/master/javascript) +- **REI**: [reidev/js-style-guide](https://github.com/reidev/js-style-guide) +- **Ripple**: [ripple/javascript-style-guide](https://github.com/ripple/javascript-style-guide) +- **Shutterfly**: [shutterfly/javascript](https://github.com/shutterfly/javascript) +- **Userify**: [userify/javascript](https://github.com/userify/javascript) +- **Zillow**: [zillow/javascript](https://github.com/zillow/javascript) +- **ZocDoc**: [ZocDoc/javascript](https://github.com/ZocDoc/javascript) ## The JavaScript Style Guide Guide - - [Reference](https://github.com/airbnb/javascript/wiki/The-JavaScript-Style-Guide-Guide) +- [Reference](https://github.com/airbnb/javascript/wiki/The-JavaScript-Style-Guide-Guide) ## Contributors - - [View Contributors](https://github.com/airbnb/javascript/graphs/contributors) +- [View Contributors](https://github.com/airbnb/javascript/graphs/contributors) ## License From bb89c19e7aab2b247f2ca6a4ee210fddfa073612 Mon Sep 17 00:00:00 2001 From: John Mumm Date: Sat, 14 Jun 2014 11:26:52 -0400 Subject: [PATCH 16/19] Update indentation --- README.md | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-) diff --git a/README.md b/README.md index d0f9fd3d65..6c5dbcc216 100644 --- a/README.md +++ b/README.md @@ -48,7 +48,7 @@ ```javascript var foo = 1, - bar = foo; + bar = foo; bar = 9; @@ -62,7 +62,7 @@ ```javascript var foo = [1, 2], - bar = foo; + bar = foo; bar[0] = 9; @@ -101,8 +101,8 @@ ```javascript var len = items.length, - itemsCopy = [], - i; + itemsCopy = [], + i; // bad for (i = 0; i < len; i++) { @@ -327,8 +327,8 @@ ```javascript // bad var books = getBooks(), - peaceful = true, - library = "Alexandria"; + peaceful = true, + library = "Alexandria"; // good var books = getBooks(); @@ -702,9 +702,9 @@ // bad var leds = stage.selectAll(".led").data(data).enter().append("svg:svg").class("led", true) - .attr("width", (radius + margin) * 2).append("svg:g") - .attr("transform", "translate(" + (radius + margin) + "," + (radius + margin) + ")") - .call(tron.led); + .attr("width", (radius + margin) * 2).append("svg:g") + .attr("transform", "translate(" + (radius + margin) + "," + (radius + margin) + ")") + .call(tron.led); // good var leds = stage.selectAll(".led") @@ -713,7 +713,8 @@ .class("led", true) .attr("width", (radius + margin) * 2) .append("svg:g") - .attr("transform", "translate(" + (radius + margin) + "," + (radius + margin) + ")") + .attr("transform", "translate(" + (radius + margin) + "," + + (radius + margin)+ ")") .call(tron.led); ``` From e32a88477074bcaee42227df0b851043c26c972b Mon Sep 17 00:00:00 2001 From: John Mumm Date: Sat, 14 Jun 2014 11:36:52 -0400 Subject: [PATCH 17/19] Remove semicolon case --- README.md | 6 ------ 1 file changed, 6 deletions(-) diff --git a/README.md b/README.md index 6c5dbcc216..880060569a 100644 --- a/README.md +++ b/README.md @@ -761,12 +761,6 @@ var name = "Ada"; return name; })(); - - // good - ;(function() { - var name = "Ada"; - return name; - })(); ``` **[⬆ back to top](#table-of-contents)** From 61f65ce2474bbee0892a108191064b64b5a24301 Mon Sep 17 00:00:00 2001 From: John Mumm Date: Sat, 14 Jun 2014 11:42:04 -0400 Subject: [PATCH 18/19] Simplify example --- README.md | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) diff --git a/README.md b/README.md index 880060569a..5d431126fa 100644 --- a/README.md +++ b/README.md @@ -1040,12 +1040,8 @@ this.name = options.name || "no name"; } - Writer.prototype.getName = function getName() { - return this.name; - }; - Writer.prototype.toString = function toString() { - return "Writer - " + this.getName(); + return "Writer - " + this.name; }; ``` From 967f3eea51b8c6abc6fa51639c51eb775574859f Mon Sep 17 00:00:00 2001 From: John Mumm Date: Mon, 16 Jun 2014 09:31:42 -0400 Subject: [PATCH 19/19] Add for initialization and constants --- README.md | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) diff --git a/README.md b/README.md index 5d431126fa..b2fc0b89a6 100644 --- a/README.md +++ b/README.md @@ -394,6 +394,22 @@ } ``` +- Do not declare a variable when initializing a for loop. + + ```javascript + // bad + for (var i = 0; i < 10; i ++) { + // ...stuff... + } + + // good + var i; + + for (i = 0; i < 10; i ++) { + // ...stuff... + } + ``` + **[⬆ back to top](#table-of-contents)** @@ -906,6 +922,16 @@ }); ``` +- Use all caps separated by underscores for constant names + + ```javascript + // bad + cpuSpeed = 1e12; + + //good + CPU_SPEED = 1e12; + ``` + - When saving a reference to `this` use `_this`. ```javascript