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

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: one year ago

Test name	Executions per second
lodash merge	1262860.4 Ops/sec
lodash/fp merge	1017744.6 Ops/sec
custom merge	3581129.8 Ops/sec
spread	21919096.0 Ops/sec

HTML Preparation code:

<script src='https://cdn.jsdelivr.net/g/lodash@4(lodash.min.js+lodash.fp.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, }, }