Page_ClientValidate 用法

JS script

function ConfirmMe()
{
   return confirm("Do you want to proceed?");
}

ASPX

<asp:TextBox id="txtName" runat="server"/>
<asp:Button id="btnSubmit" OnClientClick="return ConfirmMe()" Text="Submit" runat="server"/>

Well, that is pretty straightforward. BUT, it goes weird when you have a validator control (eg. RequiredFieldValidator) that is used to validate the "txtName" textbox server control. For instance,

<asp:TextBox id="txtName" runat="server"/>

<asp:RequiredFieldValidator id="rq1" ControlToValidate="txtName" ErrorMessage="Name cannot be blank" Display="Dynamic" runat="server"/>

<asp:Button id="btnSubmit" OnClientClick="return ConfirmMe()" Text="Submit" runat="server"/>

Whenever you press the button with no textbox value, the client-side confirmation dialog will be invoked first before the validator message is able to show up. This isn't what we expected it to behave. I tried several ways to overcome this problem, including using CLIENT CALLBACK, disabling the CauseValidation, but it failed. Finally, I was able to find a solution by adding JUST ONE line in the JS script.

function ConfirmMe()
{
   if( Page_ClientValidate())
      return confirm('Do you want to proceed?');

   return false;
}