Run results for: getElementById vs querySelector vs getElementsByClassName vs getElementsByName

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/71.0.3578.98 Safari/537.36 OPR/58.0.3135.127

Browser: Opera 58

Operating system: Mac OS X 10.13.4

Device Platform: Desktop

Date tested: 5 years ago

Test name	Executions per second
getElementById	3931690.2 Ops/sec
getElementsByTagName	1569293.0 Ops/sec
querySelector	1874326.1 Ops/sec
getElementsByClassName	1643075.8 Ops/sec
getElementsByName	1900012.5 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