Examine source code of Hjkl Navigation

{
  "manifest_version": 2,
  "name": "Hjkl",
  "version": "1.3",
  "description": "Adds vim-style navigation keys to your web browser.",
  "icons": {
    "48": "icons/logo.png"
  },
  "browser_action": {
    "default_icon": "icons/logo.png",
    "default_popup": "popup.html",
    "default_title": "Hjkl Settings"
  },
  "permissions": [
    "storage"
  ],
  "browser_specific_settings": {
    "gecko": {
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      },
      "id": "{8bf296c4-5896-45e3-8180-b470d4790c6c}"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "js": [
        "hjkl.js",
        "popup.js"
      ]
    }
  ]
}