Run results for: Create New Object from Reduce vs. ForEach vs For vs Object.entries

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/119.0.0.0 Safari/537.36

Browser: Chrome 119

Operating system: Windows

Device Platform: Desktop

Date tested: one year ago

Test name	Executions per second
Populate object via ForEach	4044.4 Ops/sec
Populate object via Reduce	0.6 Ops/sec
Populate object via Reduce (optimized)	4102.3 Ops/sec
Populate object via For ... Of	627.1 Ops/sec
Populate object via Plain For	1449.4 Ops/sec

Script Preparation code:

var objects = Array.from(new Array(2000)).map((r, i) => ({
  id: `id-${i}`,
  propA: Array.from(new Array(20000)).map((r, i) => ({ nested: i })),
  propB: Array.from(new Array(20000)),
}));

Tests:

Populate object via ForEach
var newMapFE = {}; objects.forEach(o => { newMapFE[o.id] = o.val })
Populate object via Reduce
objects.reduce((acc, item) => ({...acc, [item.id]: item.val}), {});
Populate object via Reduce (optimized)
objects.reduce((acc, item) => { acc[item.id] = item.val; return acc; }, {});
Populate object via For ... Of
var newMapFE = {}; for (obj in objects) { newMapFE[obj.id] = obj.val }
Populate object via Object.entries (for of)
var newMapFE = {}; for (const [key, value] of Object.entries(objects)) { newMapFE[key] = value; }
Populate object via Object.entries (foreach)
var newMapFE = {}; Object.entries(objects).forEach(([key, value]) => { newMapFE[key] = value; });

Run results for: Create New Object from Reduce vs. ForEach vs For vs Object.entries

Populate object via ForEach

Populate object via Reduce

Populate object via Reduce (optimized)

Populate object via For ... Of

Populate object via Object.entries (for of)

Populate object via Object.entries (foreach)