哦，错了，是这里：http://ajax.asp.net/docs/tutorials/UpdatePanelClientScripting.aspx我理解上也有问题（前面没仔细看），是可以同时的，只是前面的回传不触发一些事件而已，sorry。 我第一次看的时候居然没有注意“until it is finished”，不知道当初是怎么看的。 Multiple postbacks where the most recent postback takes precedence, which is the default behavior. Only events for the most recent asynchronous postback are raised.Multiple postbacks where one postback is given precedence, which cancels all subsequent postbacks until it is finished. Only the initializeRequest event is raised for canceled postbacks.
数据读取完了就相当于xmlhttprequest的state＝４.这样再执行callback里面的代码.
---------------------------------------------------------------------------------同步和异步和并发回传不是一个概念，异步中回传未返回前可以在界面上输入，但同步就不可以。
详情参考：http://ajax.asp.net/docs/tutorials/ExclusiveAsyncPostback.aspx
我第一次看的时候居然没有注意“until it is finished”，不知道当初是怎么看的。
Multiple postbacks where the most recent postback takes precedence, which is the default behavior. Only events for the most recent asynchronous postback are raised.Multiple postbacks where one postback is given precedence, which cancels all subsequent postbacks until it is finished. Only the initializeRequest event is raised for canceled postbacks.