Run details:
Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/98.0.4758.80 Safari/537.36
Chrome 98
Mac OS X 10.15.7
Desktop
2 years ago
Test name Executions per second
reduce with concat 14.2 Ops/sec
flatMap 601.9 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])