Another dark mode implementation

function getUserPreference() {
    if(window.localStorage.getItem('theme')) {
      return window.localStorage.getItem('theme')
    }
    return window.matchMedia('(prefers-color-scheme: dark)').matches 
      ? 'dark' 
      : 'light'
  }
  document.documentElement.dataset.theme = getUserPreference();

const toggle = document.querySelector('.theme-changer');
toggle.onclick = function() {
    var currentTheme = document.documentElement.dataset.theme
    var targetTheme = "light";

    if (currentTheme === "light") {
        targetTheme = "dark";
    }

    document.documentElement.dataset.theme = targetTheme
    window.localStorage.setItem('theme', targetTheme);
};