Run results for: querySelector(tag) vs querySelector(#ID)

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/84.0.4147.89 Safari/537.36

Browser: Chrome 84

Operating system: Mac OS X 10.15.5

Device Platform: Desktop

Date tested: 4 years ago

Test name	Executions per second
querySelector by TAG	1532669.9 Ops/sec
querySelector by ID	1018262.8 Ops/sec

HTML Preparation code:

<html>

<head>
    <title>Title</title>
    <script></script>
</head>

<body>
    <nav id="menu"></nav>
    <header id="h"></header>
    <main id="content">
      <article></article>
  	</main>
    <footer></footer>
</body>

</html>

Tests:

querySelector by TAG
document.querySelectorAll('HEADER')
querySelector by ID
document.querySelectorAll('#h')

Run results for: querySelector(tag) vs querySelector(#ID)

test querySelector by tag against ID when only one element of that tag name exists

querySelector by TAG

querySelector by ID