//Array.prototype.flat()

/**

* The flat() method creates a new array with all sub-array elements concatenated into it recursively up to the specified depth.

* depth Optional -The depth level specifying how deep a nested array structure should be flattened. Defaults to 1.

*/

let numbers = [

1,

2,

[3, 4, 5],

[6, 7],

8,

9,

[

[10, 11],

[12, 13],

],

]

let arr = numbers.flat(2)

console.log(arr)

const arr1 = [0, 1, 2, [3, 4]]

console.log(arr1.flat())

// expected output: [0, 1, 2, 3, 4]

const arr2 = [0, 1, 2, [[[3, 4]]],[{4:{},5:{}}]]

console.log(arr2.flat(3))

// expected output: [0, 1, 2, [3, 4]]

const arr4 = [1, 2, [3, 4, [5, 6, [7, 8, [9, 10]]]]];

arr4.flat(Infinity);

// [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]