Run results for: _.union VS. indexOf + push

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.102 Safari/537.36 OPR/57.0.3098.106

Browser: Opera 57

Operating system: Windows

Device Platform: Desktop

Date tested: 5 years ago

Test name	Executions per second
_.union	702.0 Ops/sec
indexOf + push	33989.1 Ops/sec

HTML Preparation code:

<script src="https://cdn.jsdelivr.net/lodash/4.17.11/lodash.min.js"></script>

Script Preparation code:

var arr = [];
var add = _.range(100);
add = add.concat(add);

Tests:

_.union
add.forEach(function (item) { arr = _.union(arr, [item]); });
indexOf + push
add.forEach(function (item) { if(arr.indexOf(item) === -1) { arr.push(item); } });