Examine source code of ReverseKey

{
  "manifest_version": 3,
  "name": "ReverseKey",
  "description": "A React.js project using Webpack to reverse keyboard layout(QWERTY placement,support for shift (+KANA) state) of selected text on page or through putting it in popup window",
  "version": "1.0.1",
  "browser_specific_settings": {
    "gecko": {
      "id": "reverseKey@alexsdev.com"
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "storage",
    "scripting",
    "activeTab",
    "menus"
  ],
  "action": {
    "default_title": "ReverseKey",
    "default_popup": "index.html",
    "default_icon": {
      "48": "icon-48.png",
      "96": "icon-96.png"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content-script.js"
      ],
      "all_frames": true,
      "match_about_blank": true
    }
  ],
  "icons": {
    "48": "icon-48.png",
    "96": "icon-96.png"
  }
}