Run results for: typeof undefined vs falsey/truthy

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/129.0.0.0 Safari/537.36

Browser: Chrome 129

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: one year ago

!!val

10.3M/s

!val

10.0M/s

typeof val !== 'undefined'

9.9M/s

typeof val === 'undefined'

9.7M/s

View exact numbers

Test name	Executions per second
✓ !!val	10,258,979 Ops/sec
!val	10,022,835 Ops/sec
typeof val !== 'undefined'	9,913,581 Ops/sec
typeof val === 'undefined'	9,744,942 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