Examine source code of Word Goblin

{
  "manifest_version": 2,
  "name": "Word Goblin",
  "version": "1.6",
  "description": "Swaps out words in your browser with a dictionary of your choice to assist in language learning.",
  "homepage_url": "https://word-goblin.web.app",
  "icons": {
    "48": "icons/word-goblin-48.png",
    "96": "icons/word-goblin-96.png"
  },
  "permissions": [
    "storage"
  ],
  "content_scripts": [
    {
      "matches": [
        "https://word-goblin.web.app/",
        "*://forums.somethingawful.com/showthread*",
        "*://www.reddit.com/*/comments/*",
        "*://old.reddit.com/*/comments/*",
        "*://news.ycombinator.com/item*",
        "*://www.nytimes.com/*",
        "*://*.medium.com/*"
      ],
      "js": [
        "word-goblin.js"
      ]
    }
  ],
  "options_ui": {
    "page": "options/options.html",
    "browser_style": true
  },
  "browser_action": {
    "default_icon": {
      "48": "icons/word-goblin-48.png"
    },
    "default_title": "Word Goblin",
    "default_popup": "popup/popup.html"
  }
}