Examine source code of LookItUp

{
  "manifest_version": 2,
  "name": "LookItUp",
  "version": "1.2.0",
  "description": "Look It Up is an extension designed to help you find things on the web faster.\n Simply, select text you want to search, right-click selected text and Look It Up!\n \n \n It allows you to search on: Google, Maps, Translate, Wikipedia, Youtube",
  "author": "Ivan B. & Susanne S.",
  "icons": {
    "48": "data/Lookitup-48.png",
    "96": "data/Lookitup-96.png"
  },
  "background": {
    "scripts": [
      "lookitup-main.js"
    ]
  },
  "permissions": [
    "activeTab",
    "contextMenus",
    "clipboardWrite"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "@lookitup"
    }
  }
}