Chrome extension – Not finding any DOM element – Blancer.com Tutorials and projects

For this Chrome extension, any DOM element I try to retrieve comes back as null. I’ve tried a few different websites and tried retrieving DOM elements through ID, class, and name. Below is the latest attempt on wikipedia.org

manifest.json

{
    "manifest_version": 3,
    "name": "Test",
    "version": "1.0",
    "description": "testing",
    "content_scripts": [
        {
            "run_at": "document_end",
            "js": ["scripts/content.js"],
            "matches": [
                "*://*.wikipedia.org/*",
                "*://wikipedia.com/*"
            ]
        }
    ],
    "action": {
        "default_popup": "hello.html"
    }
}

hello.html

<html>
  <body>
    <h1>Hello Extensions</h1>
    <script src="./scripts/content.js"></script>
  </body>
</html>

content.js

document.addEventListener('DOMContentLoaded', function() {
  const domElem = document.getElementById('www-wikipedia-org')
  console.log(domElem);
});

window.onload = function() {
  const domElem = document.getElementById('www-wikipedia-org')
  console.log(domElem);
}