function loadInto(id, url) {
  var el = document.getElementById(id);
  if (!el) return;
  fetch(url)
    .then(function (res) {
      if (!res.ok) throw new Error(res.status);
      return res.text();
    })
    .then(function (html) {
      el.innerHTML = html;
    })
    .catch(function () {});
}

document.addEventListener("DOMContentLoaded", function () {
  loadInto("header", "./components/header.html");
  loadInto("footer", "./components/footer.html");
  loadInto("message", "./components/message.html");
});