getElementsByClassName VS querySelectorAll

JavaScript performance comparison

Revision 70 of this test case created by D4Tocchini

Info

I wanted to see how well does jQuery performs on class selectors .. and boy, it was such a dissapointment

Preparation code

<script src="//ajax.googleapis.com/ajax/libs/jquery/1.8.1/jquery.min.js">
</script>
<div>
  <ul>
    <li>
      <a href="#" name="name" class="classname">item 1</a>
    </li>
    <li>
      <a href="#" name="name" class="classname">item 2</a>
    </li>
    <li>
      <a href="#" name="name" class="classname">item 3</a>
    </li>
    <li>
      <a href="#" name="name" class="classname">item 4</a>
    </li>
    <li>
      <a href="#" name="name" class="classname">item 5</a>
    </li>
    <li>
      <a href="#" name="name" class="classname">item 6</a>
    </li>
    <li>
      <a href="#" name="name" class="classname">item 7</a>
    </li>
    <li>
      <a href="#" name="name" class="classname">item 8</a>
    </li>
    <li>
      <a href="#" name="name" class="classname">item 9</a>
    </li>
    <li>
      <a href="#" name="name" class="classname">item 10</a>
    </li>
  </ul>
</div>
<script>
  var nodes;
</script>

Preparation code output

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Testing in unknown unknown
Test Ops/sec
byClassName
nodes = document.getElementsByClassName('classname');

var list = [];
for (var i=0; i<nodes.length; i++) {
  list.push(nodes[i]);
}
pending…
querySelectorAll '[class=]'
nodes = document.querySelectorAll('[class = classname]');

var list = [];
for (var i=0; i<nodes.length; i++) {
  list.push(nodes[i]);
}
pending…
jQuery $(.class)
nodes = $(".classname");

var list = [];
for (var i=0; i<nodes.length; i++) {
  list.push(nodes[i]);
}
 
pending…
querySelectorAll (.class)
nodes = document.querySelectorAll('.classname');

var list = [];
for (var i=0; i<nodes.length; i++) {
  list.push(nodes[i]);
}
pending…
byClassName cached
if (!window.livenodes) {
  window.livenodes = document.getElementsByClassName('classname');
}
nodes = window.livenodes;

var list = [];
for (var i=0; i<nodes.length; i++) {
  list.push(nodes[i]);
}
pending…

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