Run results for: jsj2 undefined vs. typeof vs. in vs. hasOwnProperty - MeasureThat.net

Run details:

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/109.0.0.0 Safari/537.36

Browser: Chrome 109

Operating system: Linux

Device Platform: Desktop

Date tested: one year ago

Test name	Executions per second
typeof a.1	18182710.0 Ops/sec
typeof b.1	18223420.0 Ops/sec
typeof a.2	18295730.0 Ops/sec
typeof b.2	18457900.0 Ops/sec
typeof a.3	18552180.0 Ops/sec
typeof b.3	18405580.0 Ops/sec

Website performance monitoring

Script Preparation code:

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

Tests:

typeof a.1
typeof obj.d === 'undefined'
typeof b.1
'undefined' === typeof obj.d;
typeof a.2
typeof obj.d === 'undefined'
typeof b.2
'undefined' === typeof obj.d;
typeof a.3
typeof obj.d === 'undefined'
typeof b.3
'undefined' === typeof obj.d;