Examine source code of MAL Not Interested

{
  "name": "MAL Not Interested",
  "version": "0.1",
  "description": "Adds a 'Not Interested' option to MyAnimeList entries",
  "manifest_version": 3,
  "content_scripts": [
    {
      "matches": [
        "https://myanimelist.net/*"
      ],
      "js": [
        "mal_not_interested.js"
      ]
    }
  ],
  "host_permissions": [
    "https://myanimelist.net/*"
  ],
  "permissions": [
    "storage"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{b6e4d711-691a-2993-d556-a59ea4cae84b}"
    }
  }
}