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

Run details:

User agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:59.0) Gecko/20100101 Firefox/59.0

Browser: Firefox 59

Operating system: Windows 7

Device Platform: Desktop

Date tested: 3 years ago

Test name	Executions per second
in operator	145776560.0 Ops/sec
!==undefined comparison	118959616.0 Ops/sec

Script Preparation code:

var obj={prop:'dddd'};

Tests: