Examine source code of Check Wordpress Version

{
  "name": "WPscan - WordPress Vulnerability Scanner",
  "version": "1.8.1",
  "description": "WordPress Vulnerability Scanner - Scan for vulnerabilities, version, themes, plugins and much more!",
  "manifest_version": 2,
  "icons": {
    "16": "images/logo_16.png",
    "32": "images/logo_32.png",
    "48": "images/logo_48.png",
    "128": "images/logo_128.png"
  },
  "background": {
    "page": "html/background.html"
  },
  "browser_action": {
    "default_popup": "html/popup.html",
    "default_title": "WPscan - WordPress Scanner",
    "default_icon": {
      "16": "images/logo_16.png",
      "32": "images/logo_32.png",
      "48": "images/logo_48.png",
      "128": "images/logo_128.png"
    }
  },
  "permissions": [
    "tabs",
    "activeTab",
    "https://*/*",
    "http://*/*",
    "webRequest"
  ],
  "applications": {
    "gecko": {
      "id": "@checkwpversion",
      "strict_min_version": "57.0"
    }
  },
  "content_security_policy": "script-src 'self'; object-src 'self'",
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "js": [
        "js/content.js",
        "js/include.js"
      ],
      "run_at": "document_start"
    }
  ],
  "web_accessible_resources": [
    "resources/Quicksand-Regular.ttf"
  ]
}