getElementsByClassName VS querySelectorAll

JavaScript performance comparison

Revision 73 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(className, node) {
    var list = node.getElementsByTagName('*'),
      length = list.length,
      result = [],
      i;
  
    for (i = 0; i < length; i++) {
      if (list[i].className.search('\\b' + className + '\\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

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

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Revisions

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