ASP.NET 2.0中控件的简单异步回调

protected override void RenderContents(HtmlTextWriter output) 
{ 
　output.RenderBeginTag(HtmlTextWriterTag.Div); 
　output.AddAttribute(HtmlTextWriterAttribute.Type, "text"); 
　output.AddAttribute(HtmlTextWriterAttribute.Id, this.ClientID); 
　output.AddAttribute(HtmlTextWriterAttribute.Name, this.ClientID); 
　output.AddAttribute(HtmlTextWriterAttribute.Value, this.Text); 
　output.AddAttribute("OnBlur", "ClientCallback();"); 
　this.AddAttributesToRender(output); 
　output.RenderBeginTag(HtmlTextWriterTag.Input); 
　output.RenderEndTag(); 
　output.RenderEndTag(); 
}

protected override void OnPreRe 
nder(EventArgs e) 
{ 
//Page.ClientScript.RegisterClientScriptInclude("UtilityFunctions", "JScript.js"); 
Page.ClientScript.RegisterStartupScript(typeof(Page), "ControlFocus", 
"document.getElementById('" + this.ClientID + "').focus();", true); 
Page.ClientScript.RegisterStartupScript(typeof(Page),
"ClientCallback","function ClientCallback() 
{"+"args=document.getElementById('"+this.ClientID+"').value;
"+Page.ClientScript.GetCallbackEventReference(this,
"args","CallbackHandler",null,"ErrorHandler",true)+"}"); 
//向服务器发送请求，由服务器端生成回调的客户端脚本。 
}

#region ICallbackEventHandler Members 
public string RaiseCallbackEvent(string eventArgument) 
{ 
　int result; 
　if (!Int32.TryParse(eventArgument, out result)) 
　throw new Exception("The method is not implemented."); 
return "Valid Data"; 
} 
#endregion

var args; 
var ctx; 
function ValidateText(ctl) 
{ 
　if(ctl.value=='') 
　{ 
alert("Please enter a value"); 
ctl.focus(); 
　} 
} 
function CallbackHandler(args,ctx) 
{ 
　alert("The data is valid"); 
} 
function ErrorHandler(args,ctx) 
{ 
　alert("The data is not a number"); 
}