getElementsByClassName VS querySelectorAll

JavaScript performance comparison

Revision 72 of this test case created by

Preparation code

<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() {
  function getElementsByClass(classList, node) {
    var node = node || document,
      list = node.getElementsByTagName('*'),
      length = list.length,
      classArray = classList.split(/\s+/),
      classes = classArray.length,
      result = [],
      i, j
    for (i = 0; i < length; i++) {
      for (j = 0; j < classes; j++) {
        if (list[i].className.search('\\b' + classArray[j] + '\\b') != -1) {
          result.push(list[i])
          break
        }
      }
    }
  
    return result
  }

};
</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

Warning! For accurate results, please disable Firebug before running the tests. (Why?)

Java applet disabled.

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

Compare results of other browsers

Revisions

You can edit these tests or add even more tests to this page by appending /edit to the URL.

0 Comments