Examine source code of languageBeast

{
  "manifest_version": 3,
  "name": "languageBeast",
  "description": "Hold 'h' for russian, 'e' for greek, 'n' for japanese, and 'l' for english. Press 'x' for the last letter of the japanese alphabet.",
  "version": "1.5",
  "action": {
    "default_title": "languageBeast"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "service_worker": "background.js",
    "type": "module"
  },
  "permissions": [
    "activeTab",
    "scripting"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content-script.js"
      ]
    }
  ],
  "web_accessible_resources": [
    {
      "resources": [
        "transition/sound.mp3"
      ],
      "matches": [
        "<all_urls>"
      ]
    }
  ],
  "icons": {
    "16": "logo/logo-16.png",
    "48": "logo/logo-48.png",
    "128": "logo/logo-128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "@ojhaugen15-4",
      "strict_min_version": "58.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ],
        "optional": []
      }
    }
  }
}