Run results for: slice + spread vs slice + concat vs slice + mutation vs spread + mutation vs slice + splice

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/114.0.0.0 Safari/537.36

Browser: Chrome 114

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: one year ago

Script Preparation code:

var indices = [1, 100, 1000, 5000, 50000, 99000]
var list = [];
for (let i = 0; i < 1000 * 1000; i++) {
  list.push(i);
}

Tests:

slice + spread
let list2 = list; for (let i = 0; i < indices.length; i++) { list2 = [...list2.slice(0, i), 777, ...list2.slice(i + 1, Infinity)] }
slice + concat
let list2 = list; for (let i = 0; i < indices.length; i++) { list2 = [].concat(list2.slice(0, i), [777], list2.slice(i + 1, Infinity)) }
slice + mutation
let list2 = list; for (let i = 0; i < indices.length; i++) { list2 = list2.slice() list2[i] = 777; }
spread + mutation
let list2 = list; for (let i = 0; i < indices.length; i++) { list2 = [...list2] list2[i] = 777; }
splice
let list2 = list; for (let i = 0; i < indices.length; i++) { list2 = list2.slice() list2.splice(i, 1, 777) }