function gg(event) {
if (event.type == "click" && ('ontouchstart' in document.documentElement)) {
return;
}
// ... Полезный код
}
const btn = ...;
if ('ontouchstart' in document.documentElement) {
btn.addEventListener('touchstart', function() {
gg();
});
} else {
btn.addEventListener('click', function() {
gg();
});
}