getElementsByClassName VS querySelectorAll

JavaScript performance comparison

Revision 20 of this test case created by pavelrevers

Preparation code

<script src="//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

Test runner

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

Java applet disabled.

Testing in unknown unknown
Test Ops/sec
getElementsByClassName
nodes = $c('classname');
pending…
querySelectorAll
nodes = $$('.classname');
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. Here’s a list of current revisions for this page:

0 comments

Add a comment