Run results for: lodash merge vs object.assign vs spread vs deepMerge util

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:76.0) Gecko/20100101 Firefox/76.0

Browser: Firefox 76

Operating system: Mac OS X 10.15

Device Platform: Desktop

Date tested: 4 years ago

Test name	Executions per second
lodash merge	4663537.0 Ops/sec
object.assign	8282397.0 Ops/sec
spread	4101601.0 Ops/sec
deepMerge	6013726.0 Ops/sec

HTML Preparation code:


<script src='https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.5/lodash.min.js'></script>

Script Preparation code:

var deepMerge = (
  target,
  source,
) => {
  var result = target;

  Object.keys(source)
    .forEach((key) => {
      if (Array.isArray(source[key])) {
        if (source[key].length > 0) {
          result[key] = [...source[key]];
        } else {
          delete result[key];
        }
      } else if (_.isObject(source[key]) && _.isObject(target[key])) {
        result[key] = deepMerge({ ...target[key] }, source[key]);
      } else {
        result[key] = source[key];
      }
    });

  return result;
};

Tests:

lodash merge
var a = { a: 'oh', b: 'my' }; var b = { c: 'goddess' }; var c = _.merge(a, b);
object.assign
var a = { a: 'oh', b: 'my' }; var b = { c: 'goddess' }; var c = Object.assign(a, b);
spread
var a = { a: 'oh', b: 'my' }; var b = { c: 'goddess' }; var c = { ...a, ...b };
deepMerge
var a = { a: 'oh', b: 'my' }; var b = { c: 'goddess' }; var c = deepMerge(a, b);