Run results for: How to reduce an object to a sub-object fast

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:109.0) Gecko/20100101 Firefox/117.0

Browser: Firefox 117

Operating system: Windows

Device Platform: Desktop

Date tested: one year ago

Test name	Executions per second
selectReduceAssign	2198447.2 Ops/sec
selectReduceSpread	1767082.6 Ops/sec
selectReduceAddExplicitly	6550710.5 Ops/sec
selectPick	90091000.0 Ops/sec

Script Preparation code:

var source = {
  a: 0,
  b: 1,
  c: 2,
  d: 3,
  e: 4,
  f: 5,
  various: null
}

var select = ['a', 'b', 'c', 'd', 'e', 'f']

var selectReduceAssign = () =>
  select.reduce(
    (accumulator, current) =>
      Object.assign(accumulator, { [current]: source[current] }),
    {}
  )

var selectReduceSpread = () =>
  select.reduce(
    (accumulator, current) =>
      ({ ...accumulator, [current]: source[current] }),
    {}
  )

var selectReduceAddExplicitly = () =>
  select.reduce(
    (accumulator, current) =>
    {
      accumulator[current] = source[current]
      return accumulator
    },
    {}
  )

var selectPick = ({ a, b, c, d, e, f }) => ({ a, b, c, d, e, f })

Tests:

selectReduceAssign
selectReduceAssign()
selectReduceSpread
selectReduceSpread()
selectReduceAddExplicitly
selectReduceAddExplicitly()
selectPick
selectPick(source)