An example of user name detection when registering is implemented using updatepanel local refresh

Local refreshes are achieved by placing controls into updatepanel.
Foreground code:

<asp:ScriptManager ID="ScriptManager1" runat="server"> 
</asp:ScriptManager> 　　　　// Must have and write in updatepanel In front of the 
<asp:updatepanel runat="server" id="updatepanel1">
<contenttemplate>
　　<asp:textbox runat="server" id="txtname"></asp:textbox>
　　<asp:button runat="server" id="btn" text=" detection " onclick="btn_click"></asp:button>
　　<asp:label runat="server" id="tip"></asp:label> 
</contenttemplate>
</asp:updatepanel>

Background code:

protected void btn_Click(object sender, EventArgs e)
{
　　if (this.txtname.Text == "user1")
　　{
　　　　this.tip.Text = " The user name already exists ";
　　}
　　else
　　{
　　　　this.tip.Text = " User name available ";
　　}
}