Examine source code of PopUp Encyclopedia

{
  "manifest_version": 2,
  "name": "PopUp Encyclopedia",
  "version": "2.2.1",
  "description": "Popup Encyclopedia which works offline and popups when a word is double-clicked.",
  "homepage_url": "https://github.com/pncnmnp/PopUp-Encyclopedia",
  "icons": {
    "48": "icons/popup-48.png"
  },
  "permissions": [
    "https://en.wikipedia.org/w/api.php?*",
    "activeTab",
    "contextMenus"
  ],
  "browser_action": {
    "default_icon": "icons/popup-48.png",
    "default_title": "PopUp Encyclopedia",
    "default_popup": "popup/get_meaning.html"
  },
  "web_accessible_resources": [
    "popup/dictionary.txt",
    "stemmer/PorterStemmer1980.js"
  ],
  "commands": {
    "_execute_browser_action": {
      "suggested_key": {
        "default": "Alt+Shift+M"
      },
      "description": "opens the Encyclopedia"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "./popup/popup.js"
      ]
    }
  ]
}