Run results for: forEach vs reduce with group by

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:153.0) Gecko/20100101 Firefox/153.0

Browser: Firefox 153

Operating system: Windows

Device Platform: Desktop

Date tested: 13 days ago

forEach

488K/s

reduce

283K/s

View exact numbers

Test name	Executions per second
✓ forEach	487,878 Ops/sec
reduce	283,367 Ops/sec

Script Preparation code:

var keyGen = () => Math.random().toString(36).substring(2, 3);
var a = Array.from({length:100},()=>{ return { key: keyGen(), val: Math.random() } });
var b = {};

Tests:

forEach
a.forEach(e=>{ let t = b[e.key] || 0; b[e.key] = t + e.val; });
reduce
b = a.reduce((a,c)=> { let t = a[c.key] || 0; a[c.key] = t + c.val; return a; },{})