Run results for: for-in vs for-of on object

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/145.0.0.0 Safari/537.36

Browser: Chrome 145

Operating system: Windows

Device Platform: Desktop

Date tested: 6 months ago

Benchmark engine: Benchmark.js

for-in

5/s

for-of-keys

4/s

View exact numbers

Test name	Executions per second
✓ for-in	5 Ops/sec
for-of-keys	4 Ops/sec

Script Preparation code:

var obj = {
  a: 1,
  b: 2,
  c: 3,
  d: 4,
  e: 5,
  f: 6,
  g: 7,
  h: 8,
  i: 9,
};

Tests:

for-in
for (var i = 0; i < 10000; i++) { for (var key in obj) { console.log(key); } }
for-of-keys
for (var i = 0; i < 10000; i++) { for (var key of Object.keys(obj)) { console.log(key); } }