Check if the user color scheme preference is dark

Use Window.matchMedia() with the appropriate media query to check the user color scheme preference.

const prefersDarkColorScheme = () =>
  window &&
  window.matchMedia &&
  window.matchMedia('(prefers-color-scheme: dark)').matches;

// Example
prefersDarkColorScheme(); // true

Source

https://www.30secondsofcode.org/js/s/prefers-dark-color-scheme