Run results for: typeof undefined vs falsey/truthy

Run details:

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/135.0.0.0 Safari/537.36

Browser: Chrome 135

Operating system: Linux

Device Platform: Desktop

Date tested: one year ago

typeof val === 'undefined'

178.2M/s

typeof val !== 'undefined'

175.3M/s

!!val

152.2M/s

!val

99.4M/s

View exact numbers

Test name	Executions per second
✓ typeof val === 'undefined'	178,166,000 Ops/sec
typeof val !== 'undefined'	175,270,752 Ops/sec
!!val	152,172,400 Ops/sec
!val	99,374,280 Ops/sec

Script Preparation code:

const undef = undefined
function checkIsUndefined(val) {
  return typeof val === 'undefined'
}
function checkIsNotUndefined(val) {
  return typeof val !== 'undefined'
}
function checkIsTruthy(val) {
  return !!val
}
function checkIfFalsey(val) {
  return !val
}

Tests:

typeof val === 'undefined'
checkIsUndefined(undef)
typeof val !== 'undefined'
checkIsNotUndefined(undef)
!!val
checkIsTruthy(undef)
!val
checkIfFalsey(undef)

Run results for: typeof undefined vs falsey/truthy

which is faster

typeof val === 'undefined'

typeof val !== 'undefined'

!!val

!val