Examine source code of FurAffinity Fav+ Button

{
  "manifest_version": 3,
  "name": "FurAffinity Fav+ Button",
  "version": "2.31",
  "description": "Adds a Fav+ button to FurAffinity submission tiles, so you can favourite without opening each submission.",
  "permissions": [
    "storage",
    "downloads"
  ],
  "host_permissions": [
    "https://www.furaffinity.net/*"
  ],
  "background": {
    "scripts": [
      "defaults.js",
      "content/selectors.js",
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "https://www.furaffinity.net/msg/submissions/*",
        "https://www.furaffinity.net/gallery/*",
        "https://www.furaffinity.net/scraps/*",
        "https://www.furaffinity.net/favorites/*",
        "https://www.furaffinity.net/browse/*",
        "https://www.furaffinity.net/search/*"
      ],
      "js": [
        "defaults.js",
        "content/selectors.js",
        "content/cart.js",
        "content/theme.js",
        "content/pages.js",
        "content/ui.js",
        "content/selection.js",
        "content/widget.js",
        "content/bulk.js",
        "content/content.js"
      ],
      "css": [
        "content/styles.css"
      ]
    }
  ],
  "action": {
    "default_popup": "popup/popup.html",
    "default_icon": {
      "16": "icons/icon16.png",
      "32": "icons/icon32.png",
      "48": "icons/icon48.png",
      "128": "icons/icon128.png"
    }
  },
  "commands": {
    "fav-focused": {
      "suggested_key": {
        "default": "Alt+Shift+F"
      },
      "description": "Fav or unfav the focused submission"
    },
    "focus-next": {
      "suggested_key": {
        "default": "Alt+Shift+Period"
      },
      "description": "Focus the next submission"
    },
    "focus-prev": {
      "suggested_key": {
        "default": "Alt+Shift+Comma"
      },
      "description": "Focus the previous submission"
    },
    "toggle-fav-all": {
      "suggested_key": {
        "default": "Alt+Shift+A"
      },
      "description": "Start or abort a bulk fav run"
    }
  },
  "icons": {
    "16": "icons/icon16.png",
    "32": "icons/icon32.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "furaffinity-fav-plus@example.com",
      "strict_min_version": "109.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    },
    "gecko_android": {
      "strict_min_version": "136.0"
    }
  }
}