async function press() {
const res = await fetch('/press', {
    method: 'POST'
  });
  const data = await res.text();
  alert(data);
}
let isRed = false;
function redBg() {
  if (isRed === false) {
    document.body.style.background = 'red';
    isRed = true;
  }else {
    document.body.style.background = '';
    isRed = false;
  }
}