Change a website favicon dynamically using JavaScript

dynamic-favicon.js

const [month, day] = new Date().toLocaleDateString("en-US").split("/");

let favicon;
switch (month + day) {
  case "214":
    favicon = "💕";
    break;
  case "1031":
    favicon = "🎃";
    break;
  case "1225":
    favicon = "🎅🏼";
    break;
  default:
    favicon = "🌐";
}

const dynamicFavicon = (favicon) => {
  const link = document.createElement("link");
  link.rel = "shortcut icon";
  link.type = "image/svg+xml";
  link.href = "data:image/svg+xml,<svg xmlns=%22http://www.w3.org/2000/svg%22 viewBox=%220 0 100 100%22><text y=%22.9em%22 font-size=%2290%22>" +
    favicon +
    "</text></svg>";
  document.head.appendChild(link);
};
dynamicFavicon(favicon);

Source => https://w3collective.com/dynamic-favicon/