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

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/104.0.0.0 Safari/537.36

Browser: Chrome 104

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: one year ago

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 i=10000; i > 0; i--) { for (var key in obj) { result += obj[key]; } } console.log(result);
Object.keys
let result; for (var i=10000; i > 0; i--) { Object.keys(obj).forEach(key => { result += obj[key]; }); } console.log(result);
Object.keys - for loop
let result; for (var i=10000; i > 0; i--) { const keys = Object.keys(obj); for (let i = 0; i < keys.length; i++) { result += obj[keys[i]]; }; } console.log(result);
for of - Object.keys
let result; for (var i=10000; i > 0; i--) { for (const key of Object.keys(obj)) { result += obj[key]; } } console.log(result);
for of - Object.entries
let result; for (var i=10000; i > 0; i--) { for (const [key, value] of Object.entries(obj)) { result += value; } } console.log(result);