How do I detect dark mode using JavaScript?

Question

Windows and macOS now have dark mode.

For CSS I can use:

    @media (prefers-dark-interface) { 
      color:          


        

Answer 1

According to MediaQueryList - Web APIs | MDN, addListener is the correct way to listen to the change. addEventListener is not working for me on iOS 13.4.

window.matchMedia('(prefers-color-scheme: dark)').addListener(function (e) {
  console.log(`changed to ${e.matches ? "dark" : "light"} mode`)
});

Answer 2

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

To watch for changes:

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

Answer 3

You can check the CSS Media-Queries directly with Javascript

The window.matchMedia() method returns a MediaQueryList object representing the results of the specified CSS media query string. The value of the matchMedia() method can be any of the media features of the CSS @media rule, like min-height, min-width, orientation, etc.

To check if the Media-Query is true the matches property can be used

// Check to see if Media-Queries are supported
if (window.matchMedia) {
  // Check if the dark-mode Media-Query matches
  if(window.matchMedia('(prefers-color-scheme: dark)').matches){
    // Dark
  } else {
    // Light
  }
} else {
  // Default (when Media-Queries are not supported)
}

To update the color-scheme dynamically if the user would change their preference the following can be used:

function setColorScheme(scheme) {
  switch(scheme){
    case 'dark':
      // Dark
      break;
    case 'light':
      // Light
      break;
    default:
      // Default
      break;
  }
}

function getPreferredColorScheme() {
  if (window.matchMedia) {
    if(window.matchMedia('(prefers-color-scheme: dark)').matches){
      return 'dark';
    } else {
      return 'light';
    }
  }
  return 'light';
}

if(window.matchMedia){
  var colorSchemeQuery = window.matchMedia('(prefers-color-scheme: dark)');
  colorSchemeQuery.addEventListener('change', setColorScheme(getPreferedColorScheme()));
}