Run results for: in operator vs typeof vs hasOwnProperty

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/117.0.0.0 Safari/537.36

Browser: Chrome 117

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: one year ago

Test name	Executions per second
in operator	4289761.5 Ops/sec
typeof	4345792.5 Ops/sec
hasOwnProperty	3024499.2 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