Run results for: standard "for" vs "for...of"

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:147.0) Gecko/20100101 Firefox/147.0

Browser: Firefox 147

Operating system: Windows

Device Platform: Desktop

Date tested: 3 months ago

Test name	Executions per second
indexed for	314.2 Ops/sec
for...of	49.3 Ops/sec

Script Preparation code:

"use strict";

const LEN  = 1 << 18; // 262,144
const REPS = 32;

// Deterministic PRNG (LCG)
let seed = 0x12345678 | 0;
const nextInt = () => (seed = (Math.imul(seed, 1664525) + 1013904223) | 0);

const data = new Int32Array(LEN);
for (let i = 0; i < LEN; i++) data[i] = nextInt();

globalThis.__benchSink = 0;

const DATA = data;
const N = LEN;
const R = REPS;

Tests:

indexed for
let sum = 0; for (let r = 0; r < R; r++) { for (let i = 0; i < N; i++) { const newVal = DATA[i]; sum += newVal; } } globalThis.__benchSink = sum;
for...of
let sum = 0; for (let r = 0; r < R; r++) { for (const v of DATA) { sum += v; } } globalThis.__benchSink = sum;

Run results for: standard "for" vs "for...of"

indexed for

for...of