jquery.resizewithwindow.js

jQuery.fn.resizeWithWindow = function(options) {
    var settings = $.extend($.fn.resizeWithWindow.defaults, options),
        element = $(this);
    
    adjustSize(element);
    $(window).resize(function() {
        adjustSize(element);
    });

    function adjustSize(targets) {
        return targets.each(function() {

            var target = {
                    height: $(this).height(),
                    width: $(this).width()
                },
                browser = {
                    height: $(window).height(),
                    width: $(window).width()
                },
                ratio = {
                    height: target.height / browser.height,
                    width: target.width / browser.width
                };

            if (ratio.height > ratio.width) {
                $(this).css({
                           'width': 'auto',
                           'height': '100%'
                       });
                settings.container
                    .height(browser.height)
                    .width($(this).width() + settings.offset_width);
            } else {
                settings.container
                    .css('width', 'auto')
                    .height($(this).height());
                $(this)
                    .css({
                        'width': '100%',
                        'height': 'auto'
                    });
            }

            return false;
        });
    }

};

jQuery.fn.resizeWithWindow.defaults = {
    container: $(this).parent(),
    offset_width: 0
};