Can one use [removed] method to include detection of scroll direction?

Question

Can one use Window.Onscroll method to include detection of scroll direction?

Answer 1

I had trouble making this work in ie8 (although it is compliant for ie9, FF and Chrome) - all scrolls seem to be detected as horizontal.

Here is a modified script demo that also works in ie8 and may cover a few more browsers.

function scrollFunc(e) {

   function getMethod() {
        var x = 0, y = 0;
        if ( typeof( window.pageYOffset ) == 'number' ) {
          x = window.pageXOffset;
          y = window.pageYOffset;
        } 

        else if( document.body && (document.body.scrollLeft || document.body.scrollTop ) ) {
          x = document.body.scrollLeft;
          y = document.body.scrollTop;
        } 

        else if( document.documentElement && (document.documentElement.scrollLeft ||     document.documentElement.scrollTop ) ) {
          x = document.documentElement.scrollLeft;
          y = document.documentElement.scrollTop;
        }

         return [x, y];
    }

    var xy = getMethod();            
    var xMethod = xy[0];           
    var yMethod = xy[1];

    if ( typeof scrollFunc.x == 'undefined' ) {
       scrollFunc.x = xMethod;
       scrollFunc.y = yMethod;
    }

    var diffX = scrollFunc.x - xMethod;
    var diffY = scrollFunc.y - yMethod;


    if( diffX<0 ) {
       // Scroll right
    } else if( diffX>0 ) {
       // Scroll left
    } else if( diffY<0 ) {
       // Scroll down
    } else if( diffY>0 ) {
       // Scroll up
    } else {
       // First scroll event
    }
    scrollFunc.x = xMethod;
    scrollFunc.y = yMethod;
}

window.onscroll=scrollFunc​

Answer 2

With jquery, you can also register a custom scroll event which supplies the scroll change as an argument to the event handler:

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

$(window).on('scroll', function() {
    var scroll = $(window).scrollTop(),
        scroll_change = scroll - previous_scroll;
    previous_scroll = scroll;
    $(window).trigger('custom_scroll', [scroll_change]);
});

Then instead of scroll, bind to custom_scroll:

$(window).on('custom_scroll', function pos(e, scroll_change) {
    console.log(scroll_change);
});

Answer 3

If you record the scrollX and scrollY on page load and each time a scroll event occurs, then you can compare the previous values with the new values to know which direction you scrolled. Here's a proof of concept:

function scrollFunc(e) {
    if ( typeof scrollFunc.x == 'undefined' ) {
        scrollFunc.x=window.pageXOffset;
        scrollFunc.y=window.pageYOffset;
    }
    var diffX=scrollFunc.x-window.pageXOffset;
    var diffY=scrollFunc.y-window.pageYOffset;

    if( diffX<0 ) {
        // Scroll right
    } else if( diffX>0 ) {
        // Scroll left
    } else if( diffY<0 ) {
        // Scroll down
    } else if( diffY>0 ) {
        // Scroll up
    } else {
        // First scroll event
    }
    scrollFunc.x=window.pageXOffset;
    scrollFunc.y=window.pageYOffset;
}
window.onscroll=scrollFunc