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

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/73.0.3683.75 Safari/537.36

Browser: Chrome 73

Operating system: Mac OS X 10.14.3

Device Platform: Desktop

Date tested: 5 years ago

Test name	Executions per second
typeof a.1	14280550.0 Ops/sec
typeof b.1	14202220.0 Ops/sec
typeof a.2	14350360.0 Ops/sec
typeof b.2	14275530.0 Ops/sec
typeof a.3	14142420.0 Ops/sec
typeof b.3	13820520.0 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;