getElementsByClassName VS querySelectorAll

JavaScript performance comparison

Revision 20 of this test case created by pavelrevers

Preparation code

<script src="https://ajax.googleapis.com/ajax/libs/mootools/1.3/mootools-yui-compressed.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>
      
<script>
Benchmark.prototype.setup = function() {
  var App = {};
  var found = [], className, matchClass, i;
  
  var $c = function(str) {
      var nodes = document.getElementsByTagName('*');
      for (i = 0; node = nodes[i++];){
          className = node.className;
          matchClass = new RegExp('(^|\\s)'+ str +'(\\s|$)');
          if (matchClass.test(className)) found.push(node);
      }
      return found;
  };

};
</script>

Preparation code output

<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>

Test runner

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Java applet disabled.

Testing in CCBot 2.0.0 / Other 0.0.0
Test Ops/sec
getElementsByClassName
nodes = $c('classname');
pending…
querySelectorAll
nodes = $$('.classname');
pending…

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Revisions

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