完美的展现网上购书的订单，修改书单，用户注册，以及展示书的部分内容的功能，代码清楚明朗，非常适合初学javascr ipt的人去研究学习-Perfect show online book orders, modify a single book, the user register, and display part of the contents of the book features, code clarity, very suitable for beginner javascr ipt