Run results for: getElementById vs querySelector vs getElementsByClassName vs getElementsByName

Run details:

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 15_3_1 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) FxiOS/98.2 Mobile/15E148 Safari/605.1.15

Browser: Mobile Safari 15

Operating system: iOS 15.3.1

Device Platform: Mobile

Date tested: 2 years ago

Test name	Executions per second
getElementById	8017170.0 Ops/sec
getElementsByTagName	4453495.5 Ops/sec
querySelector	4456600.0 Ops/sec
getElementsByClassName	4405910.0 Ops/sec
getElementsByName	4867227.0 Ops/sec

HTML Preparation code:

<div id="testdiv">
  <div id="unique" class="unique" name="unique" data-unique="1">test</div>
</div>

Script Preparation code:

var i, imax;
var doc = document;

Tests:

getElementById
var test = doc.getElementById('testdiv').childNodes[0].innerHTML;
getElementsByTagName
var formelem = doc.getElementById('testdiv').getElementsByTagName('div')[0].innerHTML;
querySelector
var test = doc.getElementById('testdiv').querySelector('.unique').innerHTML;
getElementsByClassName
var test = doc.getElementById('testdiv').getElementsByClassName('unique')[0].innerHTML;
getElementsByName
var test = doc.getElementsByName('unique')[0].innerHTML;

Run results for: getElementById vs querySelector vs getElementsByClassName vs getElementsByName

Test performance of different ways of get just one particular DOM element

getElementById

getElementsByTagName

querySelector

getElementsByClassName

getElementsByName