Run results for: replace an array in JavaScript - splice vs push vs for

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:150.0) Gecko/20100101 Firefox/150.0

Browser: Firefox 150

Operating system: Windows

Device Platform: Desktop

Date tested: 4 months ago

Benchmark engine: Benchmark.js

for

28K/s

push

15K/s

splice

2K/s

View exact numbers

Script Preparation code:

var size = 10000;
var arr1 = [];
var arr2 = [];
for (var i = 0; i < size; i++) {
  arr1.push(i);
  arr2.push(i);
}

Tests:

push
arr2.length = 0; arr2.push(...arr1);
splice
arr2.splice(0, arr2.length, ...arr1);
for
if (arr2.length !== arr1.length) arr2.length = arr1.length; for (let i = 0, length = arr1.length; i < length; ++i) { arr2[i] = arr1[i]; }