Examine source code of LevellessAoN

{
  "manifest_version": 2,
  "name": "LevellessAoN",
  "description": "Adapts all the creatures in AoN to be levelless",
  "browser_specific_settings": {
    "gecko": {
      "id": "helper@levellessaon.com",
      "strict_min_version": "57.0"
    }
  },
  "version": "1.0",
  "options_ui": {
    "page": "optionpage.html",
    "open_in_tab": false
  },
  "permissions": [
    "storage"
  ],
  "icons": {
    "32": "icon32.png",
    "64": "icon64.png",
    "128": "icon128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "http://2e.aonprd.com/Monsters.aspx?ID=*",
        "https://2e.aonprd.com/Monsters.aspx?ID=*",
        "http://2e.aonprd.com/NPCs.aspx?ID=*",
        "https://2e.aonprd.com/NPCs.aspx?ID=*"
      ],
      "js": [
        "jquery-3.5.1.slim.min.js",
        "content.js"
      ],
      "run_at": "document_end"
    }
  ]
}