blowfish/assets/js/appearance.js

const sitePreference = document.documentElement.getAttribute("data-default-appearance");
const userPreference = localStorage.getItem("appearance");

if ((sitePreference === "dark" && userPreference === null) || userPreference === "dark") {
  document.documentElement.classList.add("dark");
}

if (document.documentElement.getAttribute("data-auto-appearance") === "true") {
  if (
    window.matchMedia &&
    window.matchMedia("(prefers-color-scheme: dark)").matches &&
    userPreference !== "light"
  ) {
    document.documentElement.classList.add("dark");
  }
  window.matchMedia("(prefers-color-scheme: dark)").addEventListener("change", (event) => {
    if (event.matches) {
      document.documentElement.classList.add("dark");
    } else {
      document.documentElement.classList.remove("dark");
    }
  });
}

window.addEventListener("DOMContentLoaded", (event) => {
  const switcher = document.getElementById("appearance-switcher");
  const switcherMobile = document.getElementById("appearance-switcher-mobile");

  updateMeta()

  if (switcher) {
    switcher.addEventListener("click", () => {
      document.documentElement.classList.toggle("dark");
      localStorage.setItem(
        "appearance",
        document.documentElement.classList.contains("dark") ? "dark" : "light"
      );
      updateMeta()
    });
    switcher.addEventListener("contextmenu", (event) => {
      event.preventDefault();
      localStorage.removeItem("appearance");
    });
  }
  if (switcherMobile) {
    switcherMobile.addEventListener("click", () => {
      document.documentElement.classList.toggle("dark");
      localStorage.setItem(
        "appearance",
        document.documentElement.classList.contains("dark") ? "dark" : "light"
      );
      updateMeta()
    });
    switcherMobile.addEventListener("contextmenu", (event) => {
      event.preventDefault();
      localStorage.removeItem("appearance");
    });
  }
});


var updateMeta = () => {
  var elem, style;
  elem = document.querySelector('body');
  style = getComputedStyle(elem);
  document.querySelector('meta[name="theme-color"]').setAttribute('content', style.backgroundColor);
}