JavaScript: JSON stringify

JavaScript has a JSON.stringify() method to cast any value to a string. It works as follows:

JSON.stringify('hello'); // => "hello" - the quotes added to string values
JSON.stringify(true);    // => true    - boolean turns into string w/o quotes
JSON.stringify(5);       // => 5

const data = { hello: 'world', is: true, nested: { count: 5 } };
JSON.stringify(data); // {"hello":"world","is":true,"nested":{"count":5}}

JSON.stringify(data, null, 2); // with (null, 2) the function will insert two spaces before key
// keys receive quotation marks
// a comma is added at the end of each line if there is a value below
// {
//   "hello": "world",
//   "is": true,
//   "nested": {
//     "count": 5
//   }
// }

stringify.js

Implement and export as default a function like JSON.stringify(), but with the following differences:

• keys and string values must be without quotes
• the line ends with the value itself, w/o a comma

Syntax:

stringify(value[, replacer[, spacesCount]])

Parameters:

• value
  • A value to transform into string
• replacer, optional
  • A string to indent before key (a white space by default)
• spacesCount, optional
  • A number of replacer characters used as white space (1 by default)

import stringify from './stringify.js';

stringify('hello'); // hello - the value is cast to a string, but doesn't have quotes
stringify(true);    // true
stringify(5);       // 5

const data = { hello: 'world', is: true, nested: { count: 5 } };
stringify(data); // the same as stringify(data, ' ', 1);
// {
//  hello: world
//  is: true
//  nested: {
//   count: 5
//  }
// }

stringify(data, '|-', 2);
// The character passed by the second argument is repeated as many times as specified by the third argument
// {
// |-|-hello: world
// |-|-is: true
// |-|-nested: {
// |-|-|-|-count: 5
// |-|-}
// }

Tips

• to better grasp how JSON.stringify() works, try it with different data and parameters in the browser console
• the tests go from simple to complex:
  • checking on primitive types
  • checking for "flat" data
  • checking for "nested" data

Implement the function from step to step, checking that the changes for more complex cases did not break the simpler ones.

• Use the repeat() method
• JSON.stringify MDN docs