Run results for: flatMap vs filter + map

Run details:

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/104.0.0.0 Safari/537.36

Browser: Chrome 104

Operating system: Linux

Device Platform: Desktop

Date tested: one year ago

Test name	Executions per second
filter + map	34.6 Ops/sec
flatMap	11.7 Ops/sec

Script Preparation code:

var length = 1000000;
var arr = Array.from(Array(length).fill(0),(n, index)=>({date: Math.round(Math.random()*length), internalId: index }) );

Tests:

filter + map
const ids = arr.filter((item) => true).map(item => item.internalId);
flatMap
const ids = arr.flatMap((item) => item.date > 1 ? item.internalId : []);