Run results for: operator `in` vs. get property by key

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/122.0.0.0 Safari/537.36

Browser: Chrome 122

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: 2 years ago

Benchmark engine: Benchmark.js

if (key in obj)

6/s

if (object[key])

5/s

View exact numbers

Test name	Executions per second
✓ if (key in obj)	6 Ops/sec
if (object[key])	5 Ops/sec

Script Preparation code:

var list = Array.from({ length: 1_000_000 }, _ => crypto.randomUUID());
var object = Object.create(null);

var x;

list.toReversed().forEach((i, idx) => {
	if (idx % 2) {
		object[i] = [0x1];
	}
});

Tests:

if (key in obj)
list.forEach((key) => { if (key in object) { x = object[key]; } });
if (object[key])
list.forEach((key) => { if (object[key]) { x = object[key]; } });