Run results for: Checking for presence of object key - MeasureThat.net

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/68.0.3440.106 Safari/537.36

Browser: Chrome 68

Operating system: Mac OS X 10.13.6

Device Platform: Desktop

Date tested: 6 years ago

Test name	Executions per second
in – first element	9439729.0 Ops/sec
in – last element	9847678.0 Ops/sec
typeof – first element	9320797.0 Ops/sec
typeof – last element	5573253.0 Ops/sec
! – first element	8294955.0 Ops/sec
! – last element	10494190.0 Ops/sec

Website performance monitoring

Script Preparation code:

var obj = {
   'first' : 1,
   'is' : 1,
   'some' : 1,
   'nice' : 1,
   'test' : 1,
   'last' : 1
}

Tests:

in – first element
if ('first' in obj) { }
in – last element
if ('last' in obj) { }
typeof – first element
if (typeof obj['first'] !== "undefined") { }
typeof – last element
if (typeof obj['last'] !== "undefined") { }
! – first element
if (!obj['first']) { }
! – last element
if (!obj['last']) { }