问在JavaScript函数中检索“Asp.net ()”值时出现确认问题

EN

<asp:Button ID="btnSaveAgreement" runat="server" UseSubmitBehavior="false" Text="Save" OnClientClick ="ConfirmSaveWithoutSendEmail(this);" />

 function ConfirmSaveWithoutSendEmail(btnToDisableWhileSubmitting)
    {           
        var IsPanelToSendEmailVisible = document.getElementById('<%= hfIsSendEmailPanelVisible.ClientID%>').value; 

        if (IsPanelToSendEmailVisible > 0)
        {
            //This section takes a confirmation "Ok/Cancel" to submit or not 
            //the data, the problem is that if I choose "Cancel", the code 
            //on the button is executed, the behavior I would except is such 
            //that selecting "Cancel"  the code on my button is not 
            //executed.

            return confirm("Do you want to save without send email?");
        }
        else
        {                
            //this section disable the button while submitting information, 
            //this section works fine.

            if (!Page_ClientValidate())
                return false;

            btnToDisableWhileSubmitting.disabled = true;
            btnToDisableWhileSubmitting.value = 'Saving...';
            return true;
        }
      }