C#代码
public partial class _Default : System.Web.UI.Page, ICallbackEventHandler
...{
private string result; protected void Page_Load(object sender, EventArgs e)
...{ if (!Page.IsPostBack) ...{ string cbReference = Page.ClientScript.GetCallbackEventReference(this, "text", "ReceiveServerData", ""); //获取一个对客户端函数的引用；调用该函数时，将启动一个对服务器端事件的客户端回调。 string callbackScript = "function dos(text){" + cbReference + ";}"; //注册客户端方法 Page.ClientScript.RegisterClientScriptBlock(this.GetType(), "dos", callbackScript, true);
} } public void RaiseCallbackEvent(string text) ...{ if (text[0] == 'c') ...{ string checkcode = (string)Session["validateCode"]; string j = text.Substring(1); checkcode = checkcode.ToLower(); j = j.ToLower(); if (j == checkcode) result = "ctrue"; else result = "cfalse"; } else if (text[0] == 'e') ...{ string j = text.Substring(1); LinkDataBase myLink = new LinkDataBase(); if (myLink.CheckEmail(j) == 1) result = "efalse"; else result = "etrue"; } else if (text[0] == 'u') ...{ string j = text.Substring(1); LinkDataBase myLink = new LinkDataBase(); if (myLink.CheckUser(j) == 1) result = "ufalse"; else result = "utrue"; } } public string GetCallbackResult() ...{ return result; } 
}
Javascript 加上下面的函数
function ReceiveServerData(text)...{ if(text=="cfalse") ...{ checkValidateCode="false2"; SetCheckValidateCode(checkValidateCode); } else if(text=="ctrue") ...{ checkValidateCode="true"; SetCheckValidateCode(checkValidateCode); } else if(text=="etrue") ...{ checkEmail="true"; SetCheckEmail(checkEmail); } else if(text=="efalse") ...{ checkEmail="false3"; SetCheckEmail(checkEmail); } else if(text=="ufalse") ...{ checkUser="false4"; SetCheckUser(checkUser); } else if(text=="utrue") ...{ checkUser="true"; SetCheckUser(checkUser); } checking=false; }
最后在Javascript 中用dos(str)调用