关于 TextBox 失去焦点事件的处理,该怎么解决

关于 TextBox 失去焦点事件的处理
textbox失去焦点要响应哪个事件？在客户端处理用onblur，在服务端处理呢？
谢谢！

[解决办法]
winform是LostFocus，不知道webapplication有没有
[解决办法]
onblur= "__dopostback(....) "
[解决办法]
ajax..

onblur= "aaa(); "

function aaa()
{
_Default.Test();
}

default.aspx
[AjaxPro.....]
public void Test()
{
.........
}
[解决办法]
// .aspx
<asp:TextBox ID= "TextBox1 " runat= "server "> </asp:TextBox>
<asp:Button ID= "Button1 " runat= "server " OnClick= "Button1_Click " Text= "我被隐藏啦 " style= "display:none " />

// .aspx.cs
protected void Page_Load(object sender, EventArgs e)
{
// 1.x
// TextBox1.Attributes[ "onblur "] = Page.GetPostBackEventReference(Button1);
// 2.0
TextBox1.Attributes[ "onblur "] = ClientScript.GetPostBackEventReference(Button1, null);
}

protected void Button1_Click(object sender, EventArgs e)
{
Response.Write(DateTime.Now);
}