Examine source code of Select All Checkboxes

{
  "manifest_version": 3,
  "name": "Select All Checkboxes",
  "version": "1.4",
  "description": "An extension to select all checkboxes with a specific class.",
  "permissions": [
    "activeTab",
    "scripting"
  ],
  "host_permissions": [
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "type": "module"
  },
  "action": {
    "default_title": "Select Checkboxes"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "select-all-checkboxes@example.com",
      "strict_min_version": "109.0"
    }
  }
}