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

Run details:

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:109.0) Gecko/20100101 Firefox/116.0

Browser: Firefox 116

Operating system: Linux

Device Platform: Desktop

Date tested: one year ago

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) } }