Examine source code of Same Site Closer

{
  "manifest_version": 3,
  "name": "Same Site Closer",
  "version": "1.0",
  "description": "Closes other tabs from the same domain.",
  "permissions": [
    "tabs"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "samesitecloser@myself.local",
      "strict_min_version": "140.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "commands": {
    "close-same-site": {
      "suggested_key": {
        "default": "Ctrl+Shift+U",
        "mac": "Command+Shift+U"
      },
      "description": "Close other tabs from this domain"
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  }
}