Run results for: querySelector vs getElementById

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/51.0.2704.79 Safari/537.36 Edge/14.14393

Browser: Chrome 51

Operating system: Windows

Device Platform: Other

Date tested: 8 years ago

Test name	Executions per second
querySelector	145677.2 Ops/sec
getElementsByClassName	3247940.5 Ops/sec

HTML Preparation code:

<html>
  <body>
    <div class="foo" id="test2"></div>
    <div class="foo2" id="test"></div>
  </body>
</html>

AخA
 
<html>
  <body>
    <div class="foo" id="test2"></div>
    <div class="foo2" id="test"></div>
  </body>
</html>

Tests:

querySelector
document.querySelector(".foo");
document.querySelector(".foo");
getElementsByClassName
document.getElementsByClassName('foo');
document.getElementsByClassName('foo');