Answer by ling for Prevent BODY from scrolling when a modal is opened

Based on this fiddle: http://jsfiddle.net/dh834zgw/1/

the following snippet (using jquery) will disable the window scroll:

 var curScrollTop = $(window).scrollTop();
 $('html').toggleClass('noscroll').css('top', '-' + curScrollTop + 'px');

And in your css:

html.noscroll{
    position: fixed;
    width: 100%;
    top:0;
    left: 0;
    height: 100%;
    overflow-y: scroll !important;
    z-index: 10;
 }

Now when you remove the modal, don't forget to remove the noscroll class on the html tag:

$('html').toggleClass('noscroll');