Examine source code of FanficDownloader

{
  "manifest_version": 2,
  "name": "FanficDownloader",
  "version": "1.1",
  "description": "Download novel in epub format from m.fanfiction.net",
  "icons": {
    "16": "fanfic_icon.webp"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "fanfiction.doktorpilman@gmail.com",
      "strict_min_version": "90.0"
    }
  },
  "permissions": [
    "activeTab"
  ],
  "background": {
    "scripts": [
      "main.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "*://m.fanfiction.net/s/*"
      ],
      "js": [
        "jszip.js",
        "FileSaver.js",
        "content.js"
      ]
    }
  ]
}