Run details:
Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/102.0.5005.125 Safari/537.36
Chrome 102
Windows
Desktop
2 years ago
Test name Executions per second
reduce with concat 7.3 Ops/sec
flatMap 163.5 Ops/sec
Script Preparation code:
AخA
 
var arr = Array(10_000).fill(0)
Tests:
  • reduce with concat

     
    arr.reduce((acc, x) => [...acc, x, x], [])
  • flatMap

     
    arr.flatMap(x => [x, x])