Examine source code of Number Filler

{
  "manifest_version": 3,
  "name": "Number Filler",
  "version": "1.2",
  "description": "Select an input field via the right-click context menu and fill it with a sequence of numbers.",
  "permissions": [
    "scripting",
    "storage",
    "contextMenus",
    "notifications"
  ],
  "host_permissions": [
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "images/icon16.png",
      "32": "images/icon32.png",
      "48": "images/icon48.png"
    }
  },
  "icons": {
    "16": "images/icon16.png",
    "32": "images/icon32.png",
    "48": "images/icon48.png",
    "128": "images/icon128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "number_filler@cympator007.com"
    }
  }
}