Deep Equal vs JSON.stringify

Benchmark created on March 28, 2025

Description

Setup

function deeEqual(a, b) {
  if (a === b) return true;

  if (a && b && typeof a == 'object' && typeof b == 'object') {
    if (a.constructor !== b.constructor) return false;

    var length, i, keys;
    if (Array.isArray(a)) {
      length = a.length;
      if (length != b.length) return false;
      for (i = length; i-- !== 0;)
        if (!deeEqual(a[i], b[i])) return false;
      return true;
    }


    if ((a instanceof Map) && (b instanceof Map)) {
      if (a.size !== b.size) return false;
      for (i of a.entries())
        if (!b.has(i[0])) return false;
      for (i of a.entries())
        if (!deeEqual(i[1], b.get(i[0]))) return false;
      return true;
    }

    if ((a instanceof Set) && (b instanceof Set)) {
      if (a.size !== b.size) return false;
      for (i of a.entries())
        if (!b.has(i[0])) return false;
      return true;
    }

    if (ArrayBuffer.isView(a) && ArrayBuffer.isView(b)) {
      length = a.length;
      if (length != b.length) return false;
      for (i = length; i-- !== 0;)
        if (a[i] !== b[i]) return false;
      return true;
    }


    if (a.constructor === RegExp) return a.source === b.source && a.flags === b.flags;
    if (a.valueOf !== Object.prototype.valueOf) return a.valueOf() === b.valueOf();
    if (a.toString !== Object.prototype.toString) return a.toString() === b.toString();

    keys = Object.keys(a);
    length = keys.length;
    if (length !== Object.keys(b).length) return false;

    for (i = length; i-- !== 0;)
      if (!Object.prototype.hasOwnProperty.call(b, keys[i])) return false;

    for (i = length; i-- !== 0;) {
      var key = keys[i];

      if (!deeEqual(a[key], b[key])) return false;
    }

    return true;
  }

  // true if both NaN, false otherwise
  return a!==a && b!==b;
};

const fooObj1 =  Array.from({length: 4000}, () => ([Math.random() * 40, Math.random() * 40]));

const fooObj1Copy = JSON.parse(JSON.stringify(fooObj1.slice()));

const fooObj3 = JSON.parse(JSON.stringify(fooObj1.slice(0, 3000))).concat(Array.from({length: 1000}, () => ([Math.random() * 40, Math.random() * 40])));


const barObj1 = Array.from({length: 4000}, () => ([Math.random() * 40, Math.random() * 40]));

Test runner

deeEqual(fooObj1, fooObj1Copy);

deeEqual(fooObj1, fooObj3);

deeEqual(fooObj1,barObj1);

JSON.stringify(fooObj1) === JSON.stringify(fooObj1Copy)

JSON.stringify(fooObj1) === JSON.stringify(fooObj3)

JSON.stringify(fooObj1) === JSON.stringify(barObj1)

Revisions

You can edit these tests or add more tests to this page by appending /edit to the URL.

• Revision 1: published on March 28, 2025