Examine source code of Word Replacer II

{
  "manifest_version": 2,
  "name": "Word Replacer II",
  "short_name": "WR II",
  "description": "Change your world one word at a time.",
  "version": "2.0.10",
  "icons": {
    "48": "images/icon_48.png",
    "128": "images/icon_128.png"
  },
  "background": {
    "scripts": [
      "event.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_icon": "images/icon_19.png",
    "default_title": "Word Replacer II",
    "default_popup": "popup.html"
  },
  "options_ui": {
    "page": "options.html",
    "open_in_tab": true
  },
  "content_scripts": [
    {
      "all_frames": true,
      "js": [
        "jquery-3.4.1.min.js",
        "content_script.js"
      ],
      "matches": [
        "<all_urls>"
      ],
      "run_at": "document_end"
    }
  ],
  "permissions": [
    "storage"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{0de57b3a-7537-4449-93ad-d8ef54b043c8}"
    }
  }
}