Run results for: for in vs iterate over keys

Run details:

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:122.0) Gecko/20100101 Firefox/122.0

Browser: Firefox 122

Operating system: Linux

Device Platform: Desktop

Date tested: 2 years ago

for in

4/s

iterate over keys

3/s

View exact numbers

Test name	Executions per second
✓ for in	4 Ops/sec
iterate over keys	3 Ops/sec

Script Preparation code:

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

Tests:

for in
for (var i=10000; i > 0; i--) { for (var key in obj) { console.log(obj[key]); } }
iterate over keys
for (var i=10000; i > 0; i--) { objKeys.forEach(key => console.log(obj[key])); }