Examine source code of BetterCacher

{
  "manifest_version": 2,
  "name": "BetterCacher",
  "version": "1.1",
  "description": "The BetterCacher Firefox extension adds a new element on geocaching.com showing whether the geocache is listed on BetterCacher or not. The extension makes it easier to see if a geocache is special.",
  "icons": {
    "16": "icon_16.png",
    "128": "icon_128.png"
  },
  "permissions": [
    "https://*.geocaching.com/*",
    "http://*.geocaching.com/*",
    "https://*.bettercacher.org/*"
  ],
  "content_scripts": [
    {
      "matches": [
        "https://*.geocaching.com/*",
        "http://*.geocaching.com/*",
        "https://*.bettercacher.org/*"
      ],
      "js": [
        "jquery.min.js",
        "background.js",
        "DOMPurify.js"
      ]
    }
  ]
}