How to disable the script on the mobile version of the site?

Question

Mobile development

Friends, help disable jq script. You need to make sure that it works only on the desktop, and turns off on the mobile.
The script itself:
jQuery('document').ready(function () {
var $top = $(".menu")
$(window).on("scroll", function () {
if ($(window).scrollTop () <= 650) {
$top.fadeIn();
} else {
$top.fadeOut()
}
});
});

Answer 1

for example like this:

jQuery('document').ready(function () {
  var $top = $(".menu");
  var isMobile = $(window).width() < 1280; // <- true, если ширина экрана меньше 1280
  $(window).on("scroll", function () {
    if (isMobile) return; // <- Если ширина экрана меньше 1280, то выходим из функции
    if ($(window).scrollTop() <= 650) {
      ...
    }
  });
});