Run results for: object property lookup: in operator vs undefined comparison

Run details:

User agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/534.57.2 (KHTML, like Gecko) Version/5.1.7 Safari/534.57.2

Browser: Safari 5

Operating system: Windows 7

Device Platform: Desktop

Date tested: 3 years ago

Test name	Executions per second
in operator	7862025.0 Ops/sec
!==undefined comparison	6192718.5 Ops/sec

Script Preparation code:

var obj={prop:'dddd'};

Tests: