Run results for: getElementById vs querySelector vs getElementsByClassName vs getElementsByName

Run details:

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 11_2_6 like Mac OS X) AppleWebKit/604.1.34 (KHTML, like Gecko) CriOS/67.0.3396.69 Mobile/15D100 Safari/604.1

Browser: Chrome Mobile iOS 67

Operating system: iOS 11.2.6

Device Platform: Mobile

Date tested: 6 years ago

Test name	Executions per second
getElementById	5099136.0 Ops/sec
getElementsByTagName	2859743.5 Ops/sec
querySelector	2463423.5 Ops/sec
getElementsByClassName	2355385.2 Ops/sec
getElementsByName	2414914.8 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