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

Run details:

User agent: Mozilla/5.0 (Linux; Android 10; Pixel 3 XL Build/QQ3A.200805.001; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/84.0.4147.125 Mobile Safari/537.36

Browser: Chrome Mobile 84

Operating system: Android

Device Platform: Mobile

Date tested: 4 years ago

Test name	Executions per second
undefined	2366584.8 Ops/sec
typeof	6446426.5 Ops/sec
in	6453468.0 Ops/sec
hasOwnProperty	5900753.0 Ops/sec
bool	6472221.5 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