jQuery class vs tag qualfied class selector (v27)

Revision 27 of this benchmark created 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 error" id="on" name="light" value="red" /> Red</li>
      <li><input type="radio" class="off error" name="light" value="yellow" /> Yellow</li>
      <li><input type="radio" class="off error" 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/1/jquery.min.js"></script>

Setup

tl=$('#traffic_light');

Test runner

Ready to run.

Testing in
TestOps/sec
class selector
$('.on')
ready
tag qualified class selector
$('input.on')
ready
#id descendant class selector
$('#traffic_light .on')
ready
#id descendant tag qualified class selector
$('#on')
ready
find
$('#traffic_light').find('.on')
ready
context
$('.on',tl)
ready
:input
$('.error').filter('input');
ready
input
$('.error:input');
ready
:visible
$('input').filter('.error');
ready

Revisions

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