Run results for: Array splice is slow

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/125.0.0.0 Safari/537.36

Browser: Chrome 125

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: 2 years ago

Test name	Executions per second
With Array.splice	4799048.0 Ops/sec
Tweaked version	15879785.0 Ops/sec

Tests:

With Array.splice
function arrayInsert(array, index, value) { array.splice(index, 0, value); } const months = ['Jan', 'March', 'April', 'June']; arrayInsert(months, 1, 'Feb');
Tweaked version
function arrayInsert(array, index, value) { let end = array.length; while (end > index) { const previousEnd = end - 1; array[end] = array[previousEnd]; end = previousEnd; } array[index] = value; } const months = ['Jan', 'March', 'April', 'June']; arrayInsert(months, 1, 'Feb');