Run results for: GroupBy equiv. without groupBy v2

Run details:

User agent: Mozilla/5.0 (Linux; Android 12; 2201116SG Build/SKQ1.211006.001; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/116.0.0.0 Mobile Safari/537.36 [FB_IAB/FB4A;FBAV/424.0.0.25.113;]

Browser: Chrome Mobile 116

Operating system: Android

Device Platform: Mobile

Date tested: one year ago

Test name	Executions per second
for-loop	848.2 Ops/sec
reduce	7684.1 Ops/sec

Script Preparation code:

var arr = []
for (let i = 0; i < 5000; i++) {
	arr.push({key: Math.round(i/100), value: i})
}

Tests:

for-loop
const keys = {} let i let len = arr.length for (let i = 0; i<len; i++) { const it = arr[i] const g = keys[it.key] if (g) { g.items.push(it) } else { keys[it.key] = {items: [], key: it.key} } }
reduce
const keys2 = {} arr.reduce((acc, it) => { const g = acc[it.key] if (g) { g.items.push(it) } else { acc[it.key] = {items: [], key: it.key} } return acc }, keys2)

Run results for: GroupBy equiv. without groupBy v2

Grouping array of objects by key without using groupBy

for-loop

reduce