Examine source code of Find next page

{
  "manifest_version": 2,
  "version": "1.2",
  "name": "Find next page",
  "description": "Go to the next page when pressing Space at the end of the page",
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "js": [
        "index.js"
      ]
    }
  ],
  "homepage_url": "https://gitlab.com/arty.name/firefox-extension-find-next-page"
}