Examine source code of NoCancer

{
  "manifest_version": 2,
  "name": "NoCancer",
  "version": "1.0.6",
  "description": "MADE FOR PERSONAL USE. Extension that redirects unusably terrible websites to their tolerable versions (i.e. from new reddit to old reddit).",
  "icons": {
    "48": "icons/nc-48.png",
    "96": "icons/nc-96.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://terraria.fandom.com/*"
      ],
      "run_at": "document_start",
      "js": [
        "js/fandom.js"
      ]
    },
    {
      "matches": [
        "*://*.twitter.com/*"
      ],
      "run_at": "document_start",
      "js": [
        "js/twitter.js"
      ]
    },
    {
      "exclude_matches": [
        "*://*.m.wikipedia.org/*",
        "*://*.m.wiktionary.org/*"
      ],
      "matches": [
        "*://*.wikipedia.org/*",
        "*://*.wiktionary.org/*"
      ],
      "run_at": "document_start",
      "js": [
        "js/wikipedia.js"
      ]
    },
    {
      "exclude_matches": [
        "*://*.reddit.com/gallery/*",
        "*://*.reddit.com/poll/*"
      ],
      "matches": [
        "*://www.reddit.com/*"
      ],
      "run_at": "document_start",
      "js": [
        "js/reddit.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{226337e8-b1ce-494e-bf7a-0fdd20e9644a}"
    }
  }
}