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

Run details:

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:145.0) Gecko/20100101 Firefox/145.0

Browser: Firefox 145

Operating system: Linux

Device Platform: Desktop

Date tested: 5 months ago

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]; }