Examine source code of Wikipedia +

{
  "name": "wikipediaplus",
  "version": "1.1.25",
  "description": "WikipediaPlus is an extension that allows you to quickly and efficiently access all relevant links on the page you're visiting.",
  "manifest_version": 2,
  "icons": {
    "96": "icon-96.6621b709.png"
  },
  "content_scripts": [
    {
      "matches": [
        "https://wikipedia.org/*",
        "https://*.wikipedia.org/*"
      ],
      "js": [
        "content.0b64b1b2.js"
      ],
      "css": [
        "content.5da5e3a3.css"
      ],
      "run_at": "document_end"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{a2e191e8-b8eb-490b-b282-9f3d2c0332bf}"
    }
  }
}