isTouchDevice

isTouchDevice.js

const isTouchDevice = () => {
  const prefixes = ['', '-webkit-', '-moz-', '-o-', '-ms-', ''];
  const mq = query => window.matchMedia(query).matches;

  if (
    'ontouchstart' in window ||
    (window.DocumentTouch && document instanceof 'DocumentTouch')
  ) {
    return true;
  }
  return mq(['(', prefixes.join('touch-enabled),('), 'heartz', ')'].join(''));
};

if (isTouchDevice()) {
  document.body.classList.add("touch");
}

From https://stackoverflow.com/questions/4817029/whats-the-best-way-to-detect-a-touch-screen-device-using-javascript