This snippet detects if current device has a touch screen

is-touch.js

// Detect touch devices
var isTouchDevice =  function isTouchDevice() {
	if (('ontouchstart' in window) || window.DocumentTouch && document instanceof DocumentTouch) { 
	    return true;
	}
	return false;
}

if ( isTouchDevice()) {
	document.body.classList.add('touch-device');
}