Run results for: undefined vs. typeof vs. in vs. hasOwnProperty

Run details:

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 17_1 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) CriOS/119.0.6045.169 Mobile/15E148 Safari/604.1

Browser: Chrome Mobile iOS 119

Operating system: iOS 17.1

Device Platform: Mobile

Date tested: one year ago

Test name	Executions per second
undefined	7980623.0 Ops/sec
typeof	24015776.0 Ops/sec
in	24027614.0 Ops/sec
hasOwnProperty	23790588.0 Ops/sec
bool	23692106.0 Ops/sec

Script Preparation code:

var obj = { a: 1, b: 2, c: 3, d: 4, e: 5 };

Tests:

undefined
undefined !== obj.d;
typeof
'undefined' !== typeof obj.d;
in
'd' in obj;
hasOwnProperty
obj.hasOwnProperty( 'd' );
bool
!! obj.d;

Run results for: undefined vs. typeof vs. in vs. hasOwnProperty

Object lookup performance

undefined

typeof

in

hasOwnProperty

bool