Run results for: Reduce and Spread vs. Foreach and Mutate

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/127.0.0.0 Safari/537.36

Browser: Chrome 127

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: one year ago

ForEach and Mutate (for .. in loop)

238K/s

Mutate with Object.assign

160K/s

Reduce and Spread

57K/s

Foreach and Mutate (Object.assign)

14K/s

View exact numbers

Test name	Executions per second
✓ ForEach and Mutate (for .. in loop)	237,613 Ops/sec
Mutate with Object.assign	159,613 Ops/sec
Reduce and Spread	57,020 Ops/sec
Foreach and Mutate (Object.assign)	13,933 Ops/sec

Script Preparation code:

var objectsArray = Array(1000).fill(() => {
  const key = Math.random().toString(36).substring(2, 5);
  const value = Math.random().toString(36).substring(2, 5);
  return {[key]: value};
});

Tests:

Reduce and Spread
var combined = objectsArray.reduce((memo, obj) => ({...memo, ...obj}), {});
ForEach and Mutate (for .. in loop)
var combined = {} objectsArray.forEach(obj => { for (key in obj) { combined[key] = obj[key]; } });
Mutate with Object.assign
var combined = Object.assign(...objectsArray)
Foreach and Mutate (Object.assign)
var combined = {} objectsArray.forEach(obj => Object.assign(combined, obj));