Keep Elements in View When Scrolling

inView.js

//keep element in view
(function($)
{
    $(document).ready( function()
    {
        var elementPosTop = $('#sidebar-ads').position().top;
        $(window).scroll(function()
        {
            var wintop = $(window).scrollTop(), docheight = $(document).height(), winheight = $(window).height();
            //if top of element is in view
            if (wintop > elementPosTop)
            {
                //always in view
                $('#sidebar-ads').css({ "position":"fixed", "top":"10px" });
            }
            else
            {
                //reset back to normal viewing
                $('#sidebar-ads').css({ "position":"inherit" });
            }
        });
    });
})(jQuery);

inView.plugin.js

/**
 *  jQuery keep element in view plugin.
 *
 *  @author      David Gitonga
 *  @copyright   Copyright (c) 2012 DeveloperDrive
 *  @license     Licensed
 *  @link        http://developerdrive.com
 *  @since       Version 1.0
 *
 */

(function($)
{
    $.fn.keepElementInView = function()
    {
        var elemPosTop = this.position().top;
        $(window).scroll(function()
        {
            var wintop = $(window).scrollTop(), docheight = $(document).height(), winheight = $(window).height();
            if (wintop > elemPosTop)
            {
                this.css({ "position":"fixed", "top":"10px" });
            }
            else
            {
                this.css({ "position":"inherit" });
            }
        });
        return this;
    };

    $(document).ready( function()
    {
        jQuery('#sidebar-ads').keepElementInView();
    });
})(jQuery);