Run results for: _.uniqueBy vs Set vs Map

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/139.0.0.0 Safari/537.36

Browser: Chrome 139

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: 11 months ago

myCopy = _.uniqBy(MyArr, (obj) => obj.a);

1.5M/s

const seen = new Set(); myCopy = MyArr.filter(item => { if (seen.has(item.a)) { return false; } seen.add(item.a); return true; });

1.5M/s

const seen = new Map(); myCopy = MyArr.filter(item => { if (seen.has(item.a)) { return false; } seen.set(item.a, true); return true; });

1.4M/s

View exact numbers

Test name	Executions per second
✓ myCopy = _.uniqBy(MyArr, (obj) => obj.a);	1,522,941 Ops/sec
const seen = new Set(); myCopy = MyArr.filter(item => { if (seen.has(item.a)) { return false; } seen.add(item.a); return true; });	1,488,106 Ops/sec
const seen = new Map(); myCopy = MyArr.filter(item => { if (seen.has(item.a)) { return false; } seen.set(item.a, true); return true; });	1,397,780 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 MyArr = Array.from(
  {
    length: 40,
  },
  () => {
    return {
      a: Math.floor(Math.random() * 40),
    };
  }
);

var myCopy = null;

Tests:

uniqBy
myCopy = _.uniqBy(MyArr, (obj) => obj.a);
Set
const seen = new Set(); myCopy = MyArr.filter(item => { if (seen.has(item.a)) { return false; } seen.add(item.a); return true; });
Map
const seen = new Map(); myCopy = MyArr.filter(item => { if (seen.has(item.a)) { return false; } seen.set(item.a, true); return true; });