Examine source code of Joyreactor UX

{
  "manifest_version": 3,
  "name": "Joyreactor UX",
  "version": "0.1.8",
  "description": "Improves user experience for the modern Joyreactor interface.",
  "icons": {
    "48": "icons/reactor-ux-48.jpeg"
  },
  "content_scripts": [
    {
      "matches": [
        "*://safereactor.cc/*",
        "*://*.safereactor.cc/*",
        "*://joyreactor.cc/*",
        "*://*.joyreactor.cc/*",
        "*://reactor.cc/*",
        "*://*.reactor.cc/*"
      ],
      "js": [
        "dist/reactor-ux.es.js"
      ],
      "run_at": "document_start"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "joyreactor.ux@lifecoderua"
    }
  }
}