// method 1
function isMobile() {
return /Android|webOS|iPhone|iPad|iPod|BlackBerry|IEMobile|Opera Mini/i.test(navigator.userAgent);
}

if (!isMobile()) {
//place script you don't want to run on mobile here

}


// method 2
if (window.matchMedia('(min-width: 768px)').matches) {
//place script you don't want to run on mobile here
}