Examine source code of Eurofurence Badger

{
  "manifest_version": 3,
  "name": "Eurofurence Badger",
  "version": "1.2.0",
  "description": "Enhances your visit to the Eurofurence website by adding 'new' badges to pages that have been updated since you last viewed them. Source: https://github.com/dogpixels/ef-badger",
  "icons": {
    "16": "img/16.png",
    "32": "img/32.png",
    "48": "img/48.png",
    "64": "img/64.png",
    "128": "img/128.png",
    "192": "img/192.png"
  },
  "content_scripts": [
    {
      "matches": [
        "https://www.eurofurence.org/*",
        "https://wwwtest.eurofurence.org/*"
      ],
      "js": [
        "js/www.eurofurence.org.js"
      ]
    }
  ],
  "permissions": [
    "storage"
  ],
  "host_permissions": [
    "https://*.eurofurence.org/*"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{e3aad59f-6619-4a02-996e-a86a38607c11}"
    }
  }
}