Run results for: filter map vs reduce vs for of vs for in vs for length

Run details:

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 17_0_3 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.0.1 Mobile/15E148 Safari/604.1

Browser: Mobile Safari 17

Operating system: iOS 17.0.3

Device Platform: Mobile

Date tested: one year ago

Test name	Executions per second
filter map	1702.0 Ops/sec
reduce	1689.0 Ops/sec
for of	1592.4 Ops/sec
for in	39.8 Ops/sec
for length	56.5 Ops/sec

Script Preparation code:

var test = []

  for(let i=1; i<200000; i++) {
    test.push({
      id: i,
      class: Math.floor(Math.random()*10)
    })
  }

Tests:

filter map
test.filter(item => item.class ==2).map(item => item.id)
reduce
test.reduce((acc, item) => { if(item.class==2) { acc.push(item.id) return acc } return acc }, [])
for of
let acc = [] for(const item of test) { if(item.class==2) { acc.push(item.id) } }
for in
let acc = [] for(const indx in test) { const item = test[indx] if(item.class==2) { acc.push(item.id) } }
for length
let acc = [] for(let i=1; i<test.length; i++) { const item = test[i] if(item.class==2) { acc.push(item.id) } }