js实现分组

            item_group:function(arr){
                var map = {},
                    nList = []
                //遍历原始数组
                for (var i = 0; i < arr.length; i++) {
                    var item = arr[i]
                    //如果map没有则在新nList中添加
                    if (!map[item.types]) {
						var face='';
                        nList.push({
                            types: item.types,
							face:face,
                            data: [item]
                        })
                        map[item.types] = item
                    } else {
                        //遍历nList
                        for (var j = 0; j < nList.length; j++) {
                            var nItem = nList[j]
                            //如查找到date符合则添加
                            if (nItem.types == item.types) {
                                nItem.data.push(item)
                                //跳出循环
                                break
                            }
                        }
                    }
                }
				return nList;
            }