'use strict';

const serialize = (obj) => {

const type = typeof obj;

if (obj === null) return 'null';

else if (type === 'string') return `'${obj}'`;

else if (type === 'number') return obj.toString();

else if (type === 'boolean') return obj.toString();

else if (type !== 'object') return obj.toString();

else if (Array.isArray(obj)) {

return `[${obj}]`;

} else {

let s = '{';

for (const key in obj) {

const value = obj[key];

if (s.length > 1) s += ',';

s += key + ':' + serialize(value);

}

return s + '}';

}

};

// Usage

const obj1 = {

field: 'Value',

subObject: {

arr: [7, 10, 2, 5],

fn: (x) => x / 2

}

};

console.log(serialize(obj1));