getElementsByClassName VS querySelectorAll

JavaScript performance comparison

Revision 87 of this test case created by

Preparation code

<script src="https://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>
      
<script>
Benchmark.prototype.setup = function() {
  var getByClass = function(str){
    if (/^\.-?[_a-zA-Z]+[_a-zA-Z0-9-]*$/.test(str))
      document.getElementsByClassName(str.substr(1));
  }

};
</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 = document.getElementsByClassName('classname');
pending…
querySelectorAll
nodes = document.querySelector('.classname');
pending…
getByClass
nodes = getByClass('.classname')
pending…

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Revisions

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