Run results for: Array.prototype.concat vs spread operator on Classlist - MeasureThat.net

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/66.0.3359.170 Safari/537.36

Browser: Chrome 66

Operating system: Windows

Device Platform: Other

Date tested: 5 years ago

Test name	Executions per second
slice	256590.7 Ops/sec
spread operator	480849.5 Ops/sec
push apply into empty array	1147930.0 Ops/sec
Array.from	369462.1 Ops/sec
Object.values	124244.7 Ops/sec

Website performance monitoring

Script Preparation code:

var classes = document.body.querySelector('[class]').classList

Tests:

slice
var other = Array.prototype.slice.call(classes);
spread operator
var other = [ ...classes ]
push apply into empty array
var other = []; [].push.apply(other, classes)
Array.from
var other = Array.from(classes);
Object.values
var other = Object.values(classes);