*.client.ts

While uncommon, you may have a file or dependency that uses module side effects in the browser. You can use *.client.ts on file names to force them out of server bundles.

// this would break the server
export const supportsVibrationAPI =
  "vibrate" in window.navigator;

Note that values exported from this module will all be undefined on the server, so the only places to use them are in useEffect and user events like click handlers.

import { supportsVibrationAPI } from "./feature-check.client.ts";

console.log(supportsVibrationAPI);
// server: undefined
// client: true | false

Refer to the Route Module section in the sidebar for more information.