Run results for: Undefined testing - MeasureThat.net

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/54.0.2840.99 Safari/537.36 OPR/41.0.2353.69

Browser: Opera 41

Operating system: Windows

Device Platform: Other

Date tested: 7 years ago

Test name	Executions per second
typeof x === "undefined"	3961102.0 Ops/sec
x === undefined	1450756.0 Ops/sec
x == undefined	1441214.0 Ops/sec
x == null	4027246.0 Ops/sec

Website performance monitoring

Script Preparation code:

var x;
var y = {};

Tests:

typeof x === "undefined"
typeof x === "undefined" typeof y === "undefined"
x === undefined
x === undefined y === undefined
x == undefined
x == undefined y == undefined
x == null
x == null y == null