Run results for: getElementById vs querySelector vs getElementsByClassName vs getElementsByName

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/80.0.3987.163 Safari/537.36 OPR/67.0.3575.137

Browser: Opera 67

Operating system: Mac OS X 10.15.4

Device Platform: Desktop

Date tested: 4 years ago

Test name	Executions per second
getElementById	7830257.5 Ops/sec
getElementsByTagName	2579437.5 Ops/sec
querySelector	3518545.5 Ops/sec
getElementsByClassName	3196875.8 Ops/sec
getElementsByName	3547596.8 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