do something when scroll up and somethin else when scroll down in jquery

Question

Hi there :)

I want to add a little down arrow on my website when users scroll down and an arrow pointing up when they scroll up.

The only thing I managed to do is this

    $(document).ready(function(){
                 $(window).scroll(function () {
                    $("#bottomArrow").show(); 
                    setTimeout(function(){ $("#bottomArrow").fadeOut() }, 2000);
            });
}); 

which does not recognize the up and down, just the "scroll".

How can I do this with jQuery ?

Thank you :)

Answer 1

You need to check which way $(document).scrollTop() has changed. You could do something like this:

$(function() {

    var prevScroll = $(document).scrollTop();

    $(window).scroll(function() {
        var newScroll = $(document).scrollTop();
        if(newScroll < prevScroll) {
            // Scrolled up
        } else {
            // Scrolled down
        }
        prevScroll = newScroll;
    });
});

Testcase here:

http://jsbin.com/arazu3/