document.head

JavaScript performance comparison

Revision 3 of this test case created by kangax and last updated

Info

How much faster is the HTML5 document.head DOM tree accessor compared to its old-school variant, document.getElementsByTagName('head')[0]?

Preparation code

<script>
  document.head = document.head || document.getElementsByTagName('head')[0];
 
  Object.defineProperty(Document.prototype, 'head2', {
   get: function() {
    return this.head || this.getElementsByTagName('head')[0]
   }
  });
</script>

Test runner

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Testing in unknown unknown
Test Ops/sec
document.getElementsByTagName('head')[0]
document.getElementsByTagName('head')[0];
pending…
document.head
document.head;
pending…
document.head via prototype
document.head2;
pending…

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