自定义orderBy字母函数

            orderedUsers: function () {
                var arr = this.users;
                for (var i = 0; i < arr.length - 1; i++) {
                    for (var j = i + 1; j < arr.length; j++) {
                        var tmp = arr[i];
                        if (arr[i].name.split('')[0] > arr[j].name.split('')[0]) {
                            tmp = arr[i];
                            arr[i] = arr[j];
                            arr[j] = tmp;
                        }
                    }
                }
                return arr;
            }