Run results for: Map vs preallocation vs slice vs spread

Run details:

User agent: Mozilla/5.0 (Android 11; Mobile; rv:88.0) Gecko/88.0 Firefox/88.0

Browser: Firefox Mobile 88

Operating system: Android

Device Platform: Mobile

Date tested: 3 years ago

Script Preparation code:

var array = Array.from(new Array(1000000), (e, i) => Math.random());

Tests:

Map
var array2 = array.map((e, i) => e);
from
var array2 = Array.from(new Array(1000000), (e, i) => array[i]);
splice
var array2 = array.slice();
spread
var array2 = [...array];
loop
var array2 = new Array(1000000).fill(0), n=array2.length; for (let i = 0; i < n; i++) array2[i] = i;