getElementsByClassName VS querySelectorAll

JavaScript performance comparison

Revision 171 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 classname2">item 1</a>
    </li>
    <li>
      <a href="#" name="name" class="classname classname2">item 2</a>
    </li>
    <li>
      <a href="#" name="name" class="classname classname2">item 3</a>
    </li>
    <li>
      <a href="#" name="name" class="classname classname2">item 4</a>
    </li>
    <li>
      <a href="#" name="name" class="classname classname2">item 5</a>
    </li>
    <li>
      <a href="#" name="name" class="classname classname2">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 filterElementListByClassName(list, excludes) {
      var result = [];
  
      for (var i = 0; i < list.length; ++i) {
          if (!(list[i].classList.contains(excludes))) {
              result.push(list[i]);
          }
      }
      return result;
  }

};
</script>

Preparation code output

<div> <ul> <li> <a href="#" name="name" class="classname classname2">item 1</a> </li> <li> <a href="#" name="name" class="classname classname2">item 2</a> </li> <li> <a href="#" name="name" class="classname classname2">item 3</a> </li> <li> <a href="#" name="name" class="classname classname2">item 4</a> </li> <li> <a href="#" name="name" class="classname classname2">item 5</a> </li> <li> <a href="#" name="name" class="classname classname2">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 = Array.prototype.slice.call(
     document.getElementsByClassName('classname')
).filter(function (elm) {
    return !(elm.classList.contains('classname2'));
});
pending…
querySelectorAll
nodes = document.querySelectorAll('.classname:not(.classname2)');
pending…
jQuery $(.class)
nodes = $(".classname").not('.classname2');
pending…
getElementsByClassName - loopFn
nodes = document.getElementsByClassName('classname');
nodes = filterElementListByClassName(nodes, 'classname2');
pending…

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