Run results for: Benchmark: flatMap vs reduce vs while

Run details:

User agent: Mozilla/5.0 (Linux; Android 8.1.0; Redmi 5 Plus Build/OPM1.171019.019; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/84.0.4147.125 Mobile Safari/537.36 [FB_IAB/FB4A;FBAV/318.0.0.39.154;]

Browser: Chrome Mobile 84

Operating system: Android 8.1.0

Device Platform: Mobile

Date tested: 3 years ago

Test name	Executions per second
flatMap	482.3 Ops/sec
reduce	122.5 Ops/sec
while	1778.9 Ops/sec

Script Preparation code:

var n = 1000

Tests:

flatMap
[...Array(n)].flatMap((x,i) => [++i,i++])
reduce
[...Array(n).keys()].reduce((acc, cur) => [...acc, ++cur, cur++], [])
while
let res = [], i=0; while(n>i++) res.push(i, i);