Run results for: Set vs Object vs Lodash union: Add items to unique array

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/121.0.0.0 Safari/537.36

Browser: Chrome 121

Operating system: Windows

Device Platform: Desktop

Date tested: 2 years ago

Test name	Executions per second
Set	1.5 Ops/sec
Object	1.5 Ops/sec
Lodash union	1.3 Ops/sec

HTML Preparation code:

<script src="https://cdn.jsdelivr.net/npm/lodash@4.17.15/lodash.min.js"></script>

Script Preparation code:

var origNumItems = 1000000; // 1 million
var newNumItems = origNumItems * 2;
var origArr = [];
var newItems = [];

function initArray(arr, numItems) {
  for (var i = 0; i <= numItems; i++) { arr.push(`Item ${i}`); }
}

initArray(origArr, origNumItems);
initArray(newItems, newNumItems);

Tests:

Set
var s = new Set(origArr); for (const i in newItems) { s.add(i); } Array.from(s);
Object
var obj = {}; for (const i in origArr) { obj[i] = true; } for (const i in newItems) { obj[i] = true; } _.keys(obj)
Lodash union
// Creating this duplicate array is needed to emulate creating the data structure that contains the new items, // which the other tests do by creating an object or set var newArr = []; for (const i in newItems) { newArr.push(i); } _.union(origArr, newArr)

Run results for: Set vs Object vs Lodash union: Add items to unique array

Union an array or 1 million items with an array of 2 million items, 1 million of which are duplicates.

Set

Object

Lodash union