Run results for: for-in vs object.keys for checking empty

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:138.0) Gecko/20100101 Firefox/138.0

Browser: Firefox 138

Operating system: Mac OS X 10.15

Device Platform: Desktop

Date tested: one year ago

for-in

139.2M/s

Object.keys

9K/s

View exact numbers

Test name	Executions per second
✓ for-in	139,170,336 Ops/sec
Object.keys	9,184 Ops/sec

Script Preparation code:

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

Tests:

for-in
for (var i=10000; i > 0; i--) { for (var key in obj) { if (key) return; } }
Object.keys
for (var i=10000; i > 0; i--) { if (!Object.keys(obj).length) return; }