载入XML中如何理解同步和异步载入

[zombiehao]

本人一新手.
刚看了书.同步异步载入.
感觉很乱.
其中异步模式中.
readystate 5个状态,具体指的是什么的?
xml文件?Dom?

谁能简单和我说下,最好结合代码.
谢谢了...

[街头小贩]

readystate 5个状态,具体指的是什么的?
re:

readyState of type unsigned short, readonly

    The state of the object. The attribute MUSt be one of the following values:

    0 Uninitialized
        The initial value.
    1 Open
        The open() method has been successfully called.
    2 Sent
        The UA successfully completed the request, but no data has yet been received.
    3 Receiving
        Immediately before receiving the message body (if any). All HTTP headers have been received.
        What about HEAD requests?
    4 Loaded
        The data transfer has been completed.

http://www.w3.org/TR/2006/WD-XMLHttpRequest-20060405/

[街头小贩]

xml文件?Dom?
re:
问的是5种状态属于xml?属于dom?
5种状态属于XMLHttpRequest Object!xml只是xhr对象请求目标对象的一种!