System Color Theme Check In JavaScript

#webdev #javascript #css #design

A few days back, I was wondering how to know if the system theme is dark or light in web using JavaScript and I found a way to detect that.

In this article, I will share the implementation that I used to check the system theme.

We will use the method matchMedia() provided by the browser's window interface.
matchMedia method expects a mediaQueryString as a parameter and it will return a MediaQueryList object.
MediaQueryList object will have a property called matches of Boolean data type.

Code



if (window.matchMedia('(prefers-color-scheme: dark)').matches) {
    // Dark Mode
}

prefers-color-scheme is a CSS media feature used to detect the system color theme.

We can also have a listener, if user changes the theme in-between.



window
   .matchMedia("(prefers-color-scheme: dark)")
   .addEventListener("change", (event) => {
       const theme = event.matches ? "dark" : "light";
   });

Let me know in the comments if you are aware of any other way to detect the system theme in web.

Originally published on blog.bibekkakati.me

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Top comments (10)

myleftshoe • Jul 24 '22

Dark mode support is still harder than it should be. Tailwind claims dark mode support out-of-the box but you still have to prefix with dark:. DaisyUI makes it a lot easier, no prefixing needed! but still leaves it up to you to do persistence. Local storage works but you can't access it in SSR. If you're using sveltekit a complete solution is described by the author of this video (youtube.com/watch?v=5A21S5mMijI)/

🚩 Atul Prajapati 🇮🇳 • Jul 24 '22

Bookmarked 🔥🔥🔥

Bibek • Jul 24 '22

Thanks

🚩 Atul Prajapati 🇮🇳 • Jul 25 '22

🙏

Andrew Baisden • Jul 23 '22

Useful code snippet.

Bibek • Jul 23 '22

Thanks 👨🏻‍💻

Krisztián Maurer • Jul 23 '22

It would be nice if all websites used this as the default color theme. In the evening some website with a pickable dark mode throws flash grenades in my face..