Run results for: in operator vs typeof vs hasOwnProperty

Run details:

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 17_0 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Mobile/21A329 Twitter for iPhone/10.7

Browser: Mobile Safari 17

Operating system: iOS 17.0

Device Platform: Mobile

Date tested: one year ago

Test name	Executions per second
in operator	7882607.5 Ops/sec
typeof	7824934.5 Ops/sec
hasOwnProperty	5120824.5 Ops/sec

Script Preparation code:


const testObj = {};

for (let i = 0; i < 1000; i++)
{
  const kvText = i + '-' + i;
  testObj[kvText] = kvText;
}


window.testObj = testObj;

Tests:

in operator
'test' in testObj; '500-500' in testObj;
typeof
typeof testObj.test !== 'undefined'; typeof testObj['500-500'] !== 'undefined';
hasOwnProperty
const hop = Object.prototype.hasOwnProperty; hop.call(testObj, 'test'); hop.call(testObj, '500-500');

Run results for: in operator vs typeof vs hasOwnProperty

We're going to measure the performance for checking the property if it exists or not.

in operator

typeof

hasOwnProperty