Run details:
Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Firefox/102.0
Firefox 102
Windows
Desktop
2 years ago
Test name Executions per second
reduce with concat 0.4 Ops/sec
flatMap 1128.9 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])