Run results for: lodash merge vs lodash/fp merge vs custom merge vs spread vs ramda merge

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/125.0.0.0 Safari/537.36

Browser: Chrome 125

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: 2 years ago

spread

18.0M/s

custom merge

3.5M/s

ramda merge

1.8M/s

lodash merge

1.3M/s

lodash/fp merge

1.0M/s

View exact numbers

Test name	Executions per second
✓ spread	17,984,896 Ops/sec
custom merge	3,542,784 Ops/sec
ramda merge	1,789,551 Ops/sec
lodash merge	1,260,953 Ops/sec
lodash/fp merge	1,019,566 Ops/sec

HTML Preparation code:

<script src='https://cdn.jsdelivr.net/g/lodash@4(lodash.min.js+lodash.fp.min.js)'></script>
<script src="//cdn.jsdelivr.net/npm/ramda@latest/dist/ramda.min.js"></script>

Script Preparation code:

var fp = _.noConflict();

function customMerge(a, b) {
  const result = {}
  for (const prop in a)
    if (a.hasOwnProperty(prop)) {
      result[prop] = b.hasOwnProperty(prop) 
        ? a[prop].constructor === Object 
          ? customMerge(a[prop], b[prop]) : b[prop] 
        : a[prop]
    }
  return result
}

Tests:

lodash merge
var a = { a: 'a', b: 'b', c: { a: 'ca', b: 'cb' }}; var b = { a: 'aa', c: {b: 'cbb'}}; var c = _.merge({}, a, b);
lodash/fp merge
var a = { a: 'a', b: 'b', c: { a: 'ca', b: 'cb' }}; var b = { a: 'aa', c: {b: 'cbb'}}; var c = fp.merge(b, a);
custom merge
var a = { a: 'a', b: 'b', c: { a: 'ca', b: 'cb' }}; var b = { a: 'aa', c: {b: 'cbb'}}; var c = customMerge(a, b)
spread
var a = { a: 'a', b: 'b', c: { a: 'ca', b: 'cb' }}; var b = { a: 'aa', c: {b: 'cbb'}}; var c = { ...a, ...b, c: { ...a.c, ...b.c, }, }
ramda merge
var a = { a: 'a', b: 'b', c: { a: 'ca', b: 'cb' }}; var b = { a: 'aa', c: {b: 'cbb'}}; var c = R.mergeDeepRight(a, b)