Examine source code of Password Strength

{
  "manifest_version": 2,
  "name": "Password Strength",
  "version": "1.4",
  "description": "Password Strength is a Firefox extension that evaluates the strength of your passwords in real-time, providing feedback to help you create stronger, more secure passwords",
  "permissions": [
    "clipboardWrite",
    "clipboardRead",
    "storage",
    "<all_urls>"
  ],
  "browser_action": {
    "default_popup": "index.html",
    "default_title": "Password Strength Checker",
    "default_icon": {
      "16": "logo.png",
      "32": "logo.png",
      "48": "logo.png",
      "128": "logo.png"
    }
  },
  "icons": {
    "16": "logo.png",
    "32": "logo.png",
    "48": "logo.png",
    "128": "logo.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{def569f2-29fc-42de-a398-e5cfd5d2e2b3}"
    }
  }
}