Run results for: Reduce and Spread vs. Foreach and Mutate 2

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/86.0.4240.198 Safari/537.36

Browser: Chrome 86

Operating system: Windows

Device Platform: Desktop

Date tested: 3 years ago

Test name	Executions per second
Reduce and Spread	21348.1 Ops/sec
ForEach and Mutate (for .. in loop)	59798.0 Ops/sec
Mutate with Object.assign	56688.5 Ops/sec
Foreach and Mutate (Object.assign)	2785.2 Ops/sec
Reduce Mutate	2795.2 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));
Reduce Mutate
var combined = objectsArray.reduce((memo, obj) => Object.assign(memo, obj), {});

Run results for: Reduce and Spread vs. Foreach and Mutate 2

Reduce and Spread

ForEach and Mutate (for .. in loop)

Mutate with Object.assign

Foreach and Mutate (Object.assign)

Reduce Mutate