getElementsByTagname("a")[0] vs. querySelector("a")

JavaScript performance comparison

Test case created by Nicholas C. Zakas

Info

Tests how quickly you can retrieve a single element on the page using getElementsByTagName("a")[0] vs. querySelector("a").

Preparation code

<ul>
<li><a href="#">Item</a></li><li><a href="#">Item</a></li><li><a href="#">Item</a></li><li><a href="#">Item</a></li><li><a href="#">Item</a></li></ul>
<script>
  var result;
</script>

Preparation code output

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Testing in unknown unknown
Test Ops/sec
Using getElementsByTagName()
result = document.getElementsByTagName("a")[0];
pending…
Using querySelector()
result = document.querySelector("a");
pending…

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