Simple custom slider

jquery.customslider.js

(function($){
    var plugin_name = 'customSlider',
    methods = {
        init: function (options) {
            return this.each(function(){
                var slider = $(this),
                data = slider.data(plugin_name),
                wrapper, menu, slides, current, width,
                current_class;
                
                if (data) {
                    return true;
                }
                
                var settings = {
                    menu: slider.find('.' + plugin_name + '-menu'),
                    wrapper: slider.find('form:first'),
                    speed: 'slow',
                    beforeSlide: function(current,slider,slides,menu,buttons){},
                    afterSlide: function(current,slider,slides,menu,buttons){},
                    current_class: 'current'
                };
                
                if (options) {
                    $.extend(settings,options);
                }
                
                settings.buttons = $.isPlainObject(settings.buttons || false) ? settings.buttons : {
                    all: settings.menu.find('a:not(.prev,.next,.first,.last)'),
                    prev: settings.menu.find('a.prev'),
                    next: settings.menu.find('a.next'),
                    first: settings.menu.find('a.first'),
                    last: settings.menu.find('a.last')
                };
                
                slider
                    .data(plugin_name,settings)
                    .css({ overflow: 'hidden' });
                
                current_class = settings.current_class;
                menu = settings.menu;
                wrapper = settings.wrapper;
                slides = wrapper.children();
                current = slides.eq(0);
                width = slider.width();
                
                slides.height(1);
                current.addClass(current_class).height('auto');
                
                slides.width(width);
                wrapper.width(slides.length*width + width);
                
                wrapper.css({ 'margin-left': slider.offset().left - current.offset().left });
                
                function slide_to (n) {
                    var current = slides.filter('.' + current_class),
                    target = slides.eq(n),
                    height = 1, continue_sliding = true;
                    
                    if (
                        !current.length ||
                        !target.length ||
                        wrapper.is('.animating') ||
                        (current.index() == n) ||
                        (n < 0) ||
                        (n >= slides.length)
                    ) {
                        return;
                    }
                    
                    continue_sliding = (settings.beforeSlide || function(){ return true; })(current,slider,slides,menu,settings.buttons);
                    
                    if (continue_sliding === false) {
                        return;
                    }
                    
                    target.height('auto');
                    height = target.height();
                    target.height(1);
                    
                    target.animate({ height: height },settings.speed);
                    
                    wrapper.addClass('animating').animate(
                        { 'margin-left': -width*n },
                        settings.speed,
                        function(){
                            current.animate({ height: 1 },settings.speed);
                            wrapper.removeClass('animating');
                            current.removeClass(current_class);
                            target.addClass(current_class);
                            
                            (settings.afterSlide || function(){})(current,slider,slides,menu,settings.buttons);
                        }
                    );
                }
                
                settings.buttons.prev.click(function(e){
                    e.preventDefault();
                    slide_to(slides.filter(current_class).index() - 1);
                    return false;
                });
                
                settings.buttons.next.click(function(e){
                    e.preventDefault();
                    slide_to(slides.filter(current_class).index() + 1);
                    return false;
                });
                
                settings.buttons.first.click(function(e){
                    e.preventDefault();
                    slide_to(0);
                    return false;
                });
                
                settings.buttons.last.click(function(e){
                    e.preventDefault();
                    slide_to(slides.length - 1);
                    return false;
                });
                
                settings.buttons.all.click(function(e){
                    e.preventDefault();
                    slide_to(settings.buttons.all.index(this));
                    return false;
                });
            });
        }
    };
    
    $.fn[plugin_name] = function (method) {
        if (methods[method]) {
            return methods[method].apply(this,Array.prototype.slice.call(arguments,1));
        }
        else if (typeof method === 'object' || ! method) {
            return methods.init.apply(this,arguments);
        }
        else {
            $.error('Method ' + method + ' does not exist on jQuery.' + plugin_name);
        }
    };
}(jQuery));

test.js

$('#pieces').customSlider({
    menu: $('#piecesNav'),
    wrapper: $('#pieces form'),
    beforeSlide: function(current,slider,slides,menu,buttons){
        console.log('Validate the following fields:');
        console.log(current.find('input, select, textarea'));
        console.log('Menu buttons:');
        console.log(buttons);
    }
});