How to do a scroll in scroll event

Question

In my site, I'm trying to detect if users scroll up; the site should go to the first page, and vice versa.

I have two pages, each page has a full screen (100vh), and both are in the middle of the screen, and I want to keep both of them in the middle all the time. If the user scrolls down, the site should go to the button.

I tried to detect if user scroll by event listener and stop it and scroll then start it again but I don't understand what happened.

This my code

var position = $(window).scrollTop();

$(window).scroll(function abc() {
  $(window).off("scroll");
  var scroll = $(window).scrollTop();
  if (scroll > position) {
    console.log("scrollDown");
    $(document).scrollTop($(document).height());
  } else {
    console.log("scrollUp");
    $(document).scrollTop(0);
  }
  position = scroll;
  $(window).on("scroll", abc);
});