Examine source code of Mashov-average

{
  "manifest_version": 2,
  "name": "MashovAverage",
  "description": "This extention scans through your grades,calculates an average and putting it on the website.",
  "version": "4.2.3",
  "icons": {
    "128": "128.png"
  },
  "browser_action": {
    "default_icon": "icom.png",
    "default_popup": "popdown.html"
  },
  "permissions": [
    "activeTab"
  ],
  "content_scripts": [
    {
      "matches": [
        "https://web.mashov.info/*"
      ],
      "js": [
        "jquery-3.4.1.js",
        "popdown.js"
      ]
    }
  ]
}