Run results for: for-in vs for of vs object.keys vs object.entries

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/18.3 Safari/605.1.15

Browser: Safari 18

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: one year ago

for-in

48.8M/s

Object.keys - for loop

32.0M/s

for of - Object.keys

28.1M/s

Object.keys - forEach

23.6M/s

for of - Object.entries

5.1M/s

View exact numbers

Script Preparation code:

var obj = {
  'a': 1,
  'b': 1,
  'c': 1,
  'd': 1,
  'e': 1,
  'f': 1,
  'g': 1
};

Tests:

for-in
let result; for (var key in obj) { result += obj[key]; }
Object.keys - forEach
let result; Object.keys(obj).forEach(key => { result += obj[key]; });
Object.keys - for loop
let result; const keys = Object.keys(obj); for (let i = 0; i < keys.length; i++) { result += obj[keys[i]]; }
for of - Object.keys
let result; for (const key of Object.keys(obj)) { result += obj[key]; }
for of - Object.entries
let result; for (const [key, value] of Object.entries(obj)) { result += value; }