从Javascr ipt 语言实现的语言核心、DOM、BOM、事件模型讲起，探讨了面向对象编程、Ajax 与Comet 服务器端通信，HTML5 表单、媒体、Canvas及Web Workers、地理定位、跨文档传递消息、客户端存储等新API，还介绍了离线应用和与维护、性能、部署相关的最佳开发实践。(From the language core, DOM, BOM and event model implemented in the Javascr ipt language, this paper discusses the object oriented programming, the communication between Ajax and Comet server, HTML5 forms, media, Canvas and Web Workers, geographic positioning, cross document transfer messages, client storage and other new API. It also introduces the offline application and maintenance, and the nature of the API. The best development practice that can be deployed and deployed.)