getElementById vs. getElementsByClassName vs. querySelector vs. jQuery vs xpath

JavaScript performance comparison

Revision 26 of this test case created

Info

Compare the speed of getElementById to getElementsByClassName to querySelector to jQuery returns of each of those selectors.

Preparation code

<script src="//ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js">
</script>
<p id="foo" class="my-foo">
  Foo
</p>
<p id="bar" class="my-bar">
  Bar
</p>
<div id="poo" class="my-poo">
  <div id="par" class="my-bar">
    <div id="paz" class="my-bar">
      <span id="baz" class="my-baz">
        Baz
      </span>
    </div>
  </div>
</div>

Preparation code output

Foo

Bar

Baz

Test runner

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Testing in unknown unknown
Test Ops/sec
getElementById
var bar = document.getElementById("bar");
var poo = document.getElementById("poo");
pending…
querySelector (ID)
var bar = document.querySelector("#bar");
var poo = document.querySelector("#poo");
pending…
jQuery ID Selector
var bar = $("#bar");
var poo = $("#poo");
pending…
getElementsByClassName
var bar = document.getElementsByClassName("my-bar");
pending…
querySelector (Class)
var poo = document.getElementById("poo").querySelector(".my-baz");
pending…
jQuery Class Selector
var bar = $(document.getElementById("poo").querySelector(".my-baz"));
pending…
xpath eval
var bar = document.evaluate("//*[@id='bar']",document,null,9,null).singleNodeValue;
pending…

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