Run results for: Array .push() vs .unshift() 2 - MeasureThat.net

Run details:

User agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:61.0) Gecko/20100101 Firefox/61.0

Browser: Firefox 61

Operating system: Ubuntu

Device Platform: Desktop

Date tested: 5 years ago

Test name	Executions per second
.unshift()	366805.5 Ops/sec
.push()	19005540.0 Ops/sec
.push() preallocated array	19603700.0 Ops/sec
.unshift() preallocated array	7276.8 Ops/sec

Website performance monitoring

Script Preparation code:

var arr = []; var arr2 = new Array(42);

Tests:

.unshift()
arr.unshift(42)
.push()
arr.push(42)
.push() preallocated array
arr2.push(42)
.unshift() preallocated array
arr2.unshift(42)