在《Pragmatic ajax(动态网站静态化) A Web 2.0 Primer 》中偶然看到对readyStae状态的介绍，感觉这个介绍很实在，摘译如下：

 0: (Uninitialized) the send( ) method has not yet been invoked.
 1: (Loading) the send( ) method has been invoked, request in progress.
 2: (Loaded) the send( ) method has completed, entire response received.
 3: (Interactive) the response is being parsed.
 4: (Completed) the response has been parsed, is ready for harvesting.

 0 － （未初始化）还没有调用send()方法
 1 － （载入）已调用send()方法，正在发送请求
 2 － （载入完成）send()方法执行完成，已经接收到全部响应内容
 3 － （交互）正在解析响应内容
 4 － （完成）响应内容解析完成，可以在客户端调用了

对于readyState的这五种状态，其他书中大都语焉不详。像《Foundations of ajax(动态网站静态化)》中，只在书中的表2-2简单地列举了状态的“名称”－－The state of the request. The five possible values are 0 = uninitialized, 1 = loading, 2 = loaded, 3 = interactive, and 4 = complete。而《ajax(动态网站静态化) in Action》中好像根本就没有提到这5种状态的细节。《Professional ajax(动态网站静态化)》中虽不尽人意，但还是有可取之处：

There are five possible values for readyState:
0 (Uninitialized): The object has been created but the open() method hasn’t been called.
1 (Loading): The open() method has been called but the request hasn’t been sent.
2 (Loaded): The request has been sent.
3 (Interactive). A partial response has been received.
4 (Complete): All data has been received and the connection has been closed.

readyState有五种可能的值：
0 (未初始化)： (xml(标准化越来越近了)HttpRequest)对象已经创建，但还没有调用open()方法。
1 (载入)：已经调用open() 方法，但尚未发送请求。
2 (载入完成)： 请求已经发送完成。
3 (交互)：可以接收到部分响应数据。
4 (完成)：已经接收到了全部数据，并且连接已经关闭。

在《Understanding ajax(动态网站静态化): Using JavaScript to Create Rich Internet Applications》中，则用下表进行了说明：

readyState Status Code
 Status of the xml(标准化越来越近了)HttpRequest Object
(0) UNINITIALIZED
未初始化 The object has been created but not initialized. (The open method has not been called.)
（xml(标准化越来越近了)HttpRequest）对象已经创建，但尚未初始化（还没有调用open方法）。
(1) LOADING
载入 The object has been created, but the send method has not been called.
（xml(标准化越来越近了)HttpRequest）对象已经创建，但尚未调用send方法。
(2) LOADED
载入完成 The send method has been called, but the status and headers are not yet available.
已经调用send方法，（HTTP响应）状态及头部还不可用。
(3) INTERACTIVE
交互 Some data has been received. Calling the responseBody and responseText properties at this state to obtain partial results will return an error, because status and response headers are not fully available.
已经接收部分数据。但若在此时调用responseBody和responseText属性获取部分结果将会产生错误，因为状态和响应头部还不完全可用。
(4) COMPLETED
完成 All the data has been received, and the complete data is available in the responseBody and responseText properties.
已经接收到了全部数据，并且在responseBody和responseText属性中可以提取到完整的数据。