jQuery class vs tag qualfied class selector (v37)

Revision 37 of this benchmark created by teppeis on

Description

Just came across this article http://www.artzstudio.com/2009/04/jquery-performance-rules/ that recommends both tag qualifying class selectors as well as descending from an id for maximum jquery performance. Thought I'd test it out on his examples, because I've learned that you never want to tag qualify ids OR classes if you don't have to (similarly to CSS). However, considering the age of the article, the way jquery works could well be different now.

Preparation HTML

<div id="content">
  <form method="post" action="/">
    <h2>Traffic Light</h2>
    <ul id="traffic_light">
      <li><input type="radio" class="on" name="light" value="red" /> Red</li>
      <li><input type="radio" class="off" name="light" value="yellow" /> Yellow</li>
      <li><input type="radio" class="off" name="light" value="green" /> Green</li>
    </ul>
    <input class="button" id="traffic_button" type="submit" value="Go" />
  </form>
</div>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.0.3/jquery.min.js"></script>

Test runner

Ready to run.

Testing in
TestOps/sec
$('.on')
$('.on')
ready
$('input.on')
$('input.on')
ready
getElementsByClassName
document.getElementsByClassName("on");
ready
querySelectorAll(".on")
document.querySelectorAll(".on");
ready
querySelectorAll("input.on")
document.querySelectorAll("input.on");
ready

Revisions

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