hugo-coder-timeline/exampleSite/assets/js/dark-mode.js

const body = document.body;
const darkModeToggle = document.getElementById('dark-mode-toggle');
const darkModeMediaQuery = window.matchMedia('(prefers-color-scheme: dark)');

// Check if user preference is set, if not check value of body class for light or dark else it means that colorsheme = auto
if (localStorage.getItem("colorscheme")) {
  setTheme(localStorage.getItem("colorscheme"));
} else if (body.classList.contains('colorscheme-light') || body.classList.contains('colorscheme-dark')) {
  setTheme(body.classList.contains("colorscheme-dark") ? "dark" : "light");
} else {
  setTheme(darkModeMediaQuery.matches ? "dark" : "light");
}

darkModeToggle.addEventListener('click', () => {
  setTheme(body.classList.contains("colorscheme-dark") ? "light" : "dark");
});

darkModeMediaQuery.addListener((event) => {
  setTheme(event.matches ? "dark" : "light");
});

function setTheme(theme) {
  body.classList.remove('colorscheme-auto');
  inverse = theme === 'dark' ? 'light' : 'dark';
  localStorage.setItem('colorscheme', theme);
  body.classList.remove('colorscheme-' + inverse);
  body.classList.add('colorscheme-' + theme);
}