.eslintrc.json

{
  // ...
  "extends": [
    // ...
    "plugin:astro/recommended"
  ],
  // ...
  "overrides": [
    {
      // Define the configuration for `.astro` file.
      "files": ["*.astro"],
      // Allows Astro components to be parsed.
      "parser": "astro-eslint-parser",
      // Parse the script in `.astro` as TypeScript by adding the following configuration.
      // It's the setting you need when using TypeScript.
      "parserOptions": {
        "parser": "@typescript-eslint/parser",
        "extraFileExtensions": [".astro"]
      },
      "rules": {
        // override/add rules settings here, such as:
        // "astro/no-set-html-directive": "error"
      }
    },
    {
      "files": ["*.ts"],
      "parser": "@typescript-eslint/parser"
    }
    // ...
  ]
}