Skip to content

How to detect dark mode using JavaScript

Detecting dark mode, and detecting mode change using JavaScript

Using CSS we can detect dark mode using the prefers-color-scheme media query.

But.. what if we have to use JavaScript? I recently stumbled on this problem, because I had some JavaScript code that added an image to the page, but I wanted to show a different image based on the light/dark mode.

Here's how we can do it.

First, detect if the matchMedia object exists (otherwise the browser does not support dark mode, and you can fall back to light mode).

Then, check if it's dark mode using

window.matchMedia('(prefers-color-scheme: dark)').matches

This will return true if dark mode is enabled.

Here's a full example, where I invert the colors of an image if it's dark mode:

const img = document.querySelector('#myimage')
if (window.matchMedia && 
    window.matchMedia('(prefers-color-scheme: dark)').matches) {"invert(100%)";

There is a problem though: what if the user changes mode while using our website?

We can detect the mode change using an event listener, like this:

window.matchMedia('(prefers-color-scheme: dark)')
      .addEventListener('change', event => {
  if (event.matches) {
    //dark mode
  } else {
    //light mode
→ Download my free JavaScript Handbook!



You might be interested in those things I do:

  • Learn to code in THE VALLEY OF CODE, your your web development manual
  • Find a ton of Web Development projects to learn modern tech stacks in practice in THE VALLEY OF CODE PRO
  • I wrote 16 books for beginner software developers, DOWNLOAD THEM NOW
  • Every year I organize a hands-on cohort course coding BOOTCAMP to teach you how to build a complex, modern Web Application in practice (next edition February-March-April-May 2024)
  • Learn how to start a solopreneur business on the Internet with SOLO LAB (next edition in 2024)
  • Find me on X

Related posts that talk about js: