add

 if (room.book.length > 0) {
                let book = room.book.reduce((result, item) => {
                    return result + item.count;
                }, 0);

                console.log(book);

                if (item.count + 1 > room.free || book === room.free) {
                    return false;
                }

                room.list.forEach(itemTest => {
                    if (itemTest.group !== item.group)  {
                        itemTest.class = 'hide';
                    }
                });

                room.book.forEach(itemTest => {
                    if (itemTest.id === item.id) {
                        itemTest.count = item.count + 1
                    } else {
                        room.book.push({
                            count: item.count + 1,
                            group: item.group,
                            id: item.id
                        });
                    }
                })

            } else {
                room.book.push({
                    count: item.count + 1,
                    group: item.group,
                    id: item.id
                });
            }

            item.count += 1;
            item.class = 'active';