Run results for: forEach concat vs reduce push performance

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/96.0.4664.110 Safari/537.36 Edg/96.0.1054.62

Browser: Chrome 96

Operating system: Windows

Device Platform: Desktop

Date tested: 3 years ago

Test name	Executions per second
forEach concat	20.4 Ops/sec
Reduce push	54.3 Ops/sec

Tests:

forEach concat

const a = [...Array(1000)].map(() => ({
    nested: Array.from({length: 40}, () => Math.floor(Math.random() * 40))
}));

let b = [];

a.forEach((item) => {
  b = b.concat(item.nested);
});

​x
 
const a = [...Array(1000)].map(() => ({    nested: Array.from({length: 40}, () => Math.floor(Math.random() * 40))}));​let b = [];​a.forEach((item) => {  b = b.concat(item.nested);});

Reduce push

const a = [...Array(1000)].map(() => ({
    nested: Array.from({length: 40}, () => Math.floor(Math.random() * 40))
}));

const b = a.reduce((acc, item) => {
  acc.push(...item.nested);
  
  return acc
}, []);

 
const a = [...Array(1000)].map(() => ({    nested: Array.from({length: 40}, () => Math.floor(Math.random() * 40))}));​const b = a.reduce((acc, item) => {  acc.push(...item.nested);    return acc}, []);