jquery漂亮大气的115网盘登录注册界面

款来自115网盘首页的登录+注册+通栏banner特效代码。
背景切换相关代码实现
var defaultInd = 0;
                    var list = $('#js_ban_content').children();
                    var count = 0;
                    var change = function(newInd, callback){
                        if(count) return;
                        count = 2;
                        $(list[defaultInd]).fadeOut(400, function(){
                            count--;
                            if(count <= 0){
                                if(start.timer) window.clearTimeout(start.timer);
                                callback && callback();
                            }
                        });
                        $(list[newInd]).fadeIn(400, function(){
                            defaultInd = newInd;
                            count--;
                            if(count <= 0){
                                if(start.timer) window.clearTimeout(start.timer);
                                callback && callback();
                            }
                        });
                    }
                    
                    var next = function(callback){
                        var newInd = defaultInd + 1;
                        if(newInd >= list.length){
                            newInd = 0;
                        }
                        change(newInd, callback);
                    }
                    
                    var start = function(){
                        if(start.timer) window.clearTimeout(start.timer);
                        start.timer = window.setTimeout(function(){
                            next(function(){
                                start();
                            });
                        }, 8000);
                    }
                    
                    start();
                    
                    $('#js_ban_button_box').on('click', 'a', function(){
                        var btn = $(this);
                        if(btn.hasClass('right')){
                            //next
                            next(function(){
                                start();
                            });
                        }
                        else{
                            //prev
                            var newInd = defaultInd - 1;
                            if(newInd < 0){
                                newInd = list.length - 1;
                            }
                            change(newInd, function(){
                                start();
                            });
                        }
                        return false;
                    });
                    
                })();