Live Demo that displays Theme Switching and Server Dates in action.

This example isn't meant to be a full-fledged application; it's more a reference for your own implementation or a starting point for your own project.

It helps you implement Theme Switching and Server Dates, based on Epic Stack - Client Hints and Jacob Paris article.

On the first visit, the server grabs theme and time-zone hints, stores them in cookies, and reloads the page for client-side usage. While the FOUC (Flash of Unstyled Content) is unavoidable, the one-time page reload is a good trade-off and provides a better user experience than having the flash occur on every page load.

Check out the Resources section for more info and examples on Client Hints.

Let's review some implementation details.

Theme switching is based on prefers-color-scheme media feature, which is a part of the User Preference Media Features specification.

To update our theme, we do a POST request to /resources/theme route, that updates the theme cookie, and either reloads the page (Progressive Enhancement) or returns a JSON response.

The time-zone implementation allows the server to understand client's time zone on initial page load. On the server-side, the getHints(request).timeZone method is used to retrieve the time-zone information. For client-side usage, useHints().timeZone could be employed.

In the App Demo, the time-zone is also displayed in the UI, and the Intl.DateTimeFormat object is created in the user's time-zone, considering their preferred language.

In order to run this example locally, clone the repository and install its dependencies:

npm install

Run the server:

npm run dev

Ready to go! 🎉

A list of examples and resources that could help you grasp the concepts behind Client Hints and this implementation.

• HTTP Client Hints - A must-read introduction to Client Hints by MDN Web Docs.
• Media features Client Hints - A great article that discusses how client hint headers can help websites obtain user media preferences like color scheme or reduced motion at request time, enabling servers to deliver optimized CSS for better performance.
• Server Dates with Remix by Jacob Paris - One of the first Remix articles that discusses how to handle date rendering in Remix apps when the server and client are in different timezones, avoiding issues like flash of unstyled content (FOUC) and hydration problems. A similar approach has later been used as base implementation for the Epic Stack - Client Hints.
• FOUC (Flash of Unstyled Content) - A great Wikipedia article that discusses the FOUC issue.
• Epic Stack - Client Hints by kentcdodds - An introduction to Client Hints + Remix, that has served as a base for this implementation.

If you have any suggestions you'd like to share, feel free to open a PR!

Licensed under the MIT license.