How detect Dark or Light mode in JS or CSS?

Any way to create an evrnt to know if we are in dark mode or light mode in JS to change an image or a filter ? (or maybe in CSS)

You can use MutationObserver to watch for changes to a DOM node’s attributes. Just add this JS to your design:

window.addEventListener('DOMContentLoaded', () => {    
    const getTheme = () => document.documentElement.getAttribute('data-bs-theme');
    let theme = getTheme();
    const observer = new MutationObserver(() => {
        theme = getTheme();
    observer.observe(document.documentElement, { attributeFilter: ["data-bs-theme"] });
    function onThemeChange(theme) {
      // Do stuff

You can add your logic for what happens when the theme changes in the onThemeChange() function.

If you want to change the appearance of a component depending on the mode, you can do it with this CSS:

[data-bs-theme=dark] .your-selector {
    /* Add your styles here */

Change .your-selector to a selector that matches the element you want to change and add your styles in the block. They will only be applied in dark mode.


Thank you.
Both working, CSS is beter for me.