webbed-site/theme.js

  var DEFAULT_THEME = "peach";
  var THEMES = [DEFAULT_THEME, "moon", "sakura", "honey"];
  
  function setTheme(theme) {
    if (THEMES.indexOf(theme) < 0) theme = DEFAULT_THEME;
    document.getElementById('switcher-id').href = '/themes/' + theme + '.css';
    localStorage.setItem('style', theme);
  }
  
  setTheme(localStorage.getItem('style'));
  
  const switches = document.getElementsByClassName('switch');
  for (const el of switches) {
    el.addEventListener('click', () => {
    setTheme(el.dataset.theme);
  });
};