# E0267: TypeScript types are not allowed in JavaScript

TypeScript type aliases can be declared with the `type` keyword. It is a syntax error to write a TypeScript type alias in JavaScript code:

    type Response<T> = {
      ok: boolean;
      error?: string;
      data?: T;
    };

To fix this error, rename your file to have a `.ts` or `.tsx` suffix.

Alternatively, use JSDoc to declare the type:

    /**
     * @typedef {Object} Response
     * @prop {boolean} ok
     * @prop {string} [error]
     * @prop {Object} data
     */

Introduced in quick-lint-js version 2.8.0.

Documentation for other errors