Run results for: Splice vs Spread vs Unshift to insert at beginning of array vs manual

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:104.0) Gecko/20100101 Firefox/104.0

Browser: Firefox 104

Operating system: Windows

Device Platform: Desktop

Date tested: 2 years ago

Script Preparation code:

var array = Array.from({ length: 100 }).map((val, i) => i);

Tests:

Splice
var newArray = array.slice(0, 0, 99);
Spread
var newArray = [99, ...array];
Unshift
var newArray = array.unshift(99);
manual
var len=array.length, item=99; while (len) { array[len] = array[len-1]; len--} array[0] = item;