[require-js]向下滑动ajax加载的javascript实现

define(function(){
	function ScrollMoreInfo($wraper , loadDataFunc , json_ids , perNum  , tpl_info)
	{
		this.$wraper = $wraper;		
		this.loadDataFunc = loadDataFunc;
		this.originIds = json_ids;
		this.tpl = tpl_info;		
		this.isAppendIng = false;
		this.perNum = perNum;
		this.leftData = [];
	}
	ScrollMoreInfo.prototype = new Hnb.event();
	$.extend(ScrollMoreInfo.prototype , {
		init: function(){
			var self = this;
			self.initData();
			self.register();
		},
		initData: function(){
			var self = this;
			self.start = self.originIds.length;
			self.isEnd = false;
			
			
			self.idRef = {};
			for(var i in self.originIds)
			{
				if(self.originIds[i]){
					self.idRef[self.originIds[i] + "_"] = true;
				}
			}
		},
		register: function(){
			var self = this;
			$(window).scroll(function(){
				var height = $(window).height();
				var top = $(window).scrollTop();
				var bodyHeight = $("#id_top_wrap").height();
				if(height + top > bodyHeight - 100) {
					//加载数据...
					self.appendMoreData();
				}
			});
			$(window).trigger("scroll");
		},
		appendMoreData: function(){
			var self = this;
           
			if(self.isAppendIng){
				return;
			}
			if(self.leftData.length >= self.perNum){
				var arr_data = self.leftData.splice(0 , self.perNum);
				self.renderData(arr_data);
			} else if(self.isEnd) {				
				if(self.leftData.length == 0){
					self.renderNoMore();
					return;
				}
				var arr_data = self.leftData.splice(0 , self.perNum);
                
				self.renderData(arr_data);
				
				if(self.leftData.length == 0){
					self.renderNoMore();
				}
			} else {
                
				//加载更多数据
				self.isAppendIng = true;
				self._loadData().fail(function(){
					self.isEnd = true;
				}).always(function(){
					self.isAppendIng = false;
					self.appendMoreData();
				});
                
			}
		},
        // 尾部图片(no-more-data / data-loading)的展示
		renderNoMore: function(){
			var self = this;
			self.$wraper.find(".c-data-no-more").removeClass("dn");
			self.$wraper.find(".c-data-loading").addClass("dn");
		},
        //  数据模板渲染
		renderData: function(arr_data){
			var self = this;
			var html = Hnb.ui.tmpl(self.tpl , {
				arr_infoList : arr_data
			});			
			self.$wraper.find(".c-data-loading").before(html);	
			self.trigger("after:render:more:data");
		},
        // 数据加载
		_loadData: function(){
			var self = this;
			var defer = $.Deferred();
			self.loadDataFunc(self.start , self.perNum).done(function(json_msg){
               
				if(json_msg.state){
					//失败，将现有数据展示到页面，设置为结束
					defer.reject(-1);
				} else {
					if(json_msg.data.infoList.length < self.perNum){
						self.isEnd = true;
					}
					self._storeData(json_msg.data.infoList);
					defer.resolve();
				}
			}).fail(function(){
				defer.reject(-1);
			});
            // 数据读取起点
			self.start += self.perNum;
			return defer;
		},
        // 当加载的数据小于每页的长度时，先存储起来
		_storeData: function(arr_data){
			var self = this;
			for(var i in arr_data)
			{
				if(arr_data[i].id && !self.idRef[arr_data[i].id + "_"])
				{
					self.leftData.push(arr_data[i]);
					self.idRef[arr_data[i].id + "_"] = true;
				}
			}
		}
	});
	
	return {
		create: function($wraper , loadDataFunc , json_dataInit , perNum  , tpl_info){
			var obj = new ScrollMoreInfo($wraper , loadDataFunc , json_dataInit , perNum  , tpl_info);
			obj.init();
			return obj;
		}
	}
});