I am trying to validate an asp textbox via javascript but I can't get the javascript code to validate the textbox control.

Textbox markup in the usercontrol:

Here is my code in the page load event that register the javascript code block

Dim cs As ClientScriptManager = Page.ClientScript
            If Not cs.IsClientScriptBlockRegistered(csType, csEmailCheck) Then
                Dim csText As New StringBuilder()
                csText.Append(Environment.NewLine + "[script removed]                 csText.Append(Environment.NewLine + "function CheckSubject(){")
                csText.Append(Environment.NewLine + "  if (document.getElementById(""<%=txtEmailSubject.ClientID%>"").value=="""")")
                csText.Append(Environment.NewLine + " {")
                csText.Append(Environment.NewLine + " var answer = confirm (""Do you want to send an email without a subject?"")")
                csText.Append(Environment.NewLine + " if (answer)")
                csText.Append(Environment.NewLine + " return true;")
                csText.Append(Environment.NewLine + " else")
                csText.Append(Environment.NewLine + " return false;")
                csText.Append(Environment.NewLine + "}")
                csText.Append(Environment.NewLine + "}")
                csText.Append(Environment.NewLine + "[script removed]")
                Page.ClientScript.RegisterClientScriptBlock(csType, csEmailCheck, csText.ToString())
            End If
            btnSendMail.Attributes.Add("onclick", "return CheckSubject()")
 

The javascript output is below

<script type="text/javascript">
function CheckSubject(){
  if (document.getElementById("<%=txtEmailSubject.ClientID%>").value=="")
 {
 var answer = confirm ("Do you want to send an email without a subject?")
 if (answer)
 return true;
 else
 return false;
}
}
script>

I know the problem is related to the way dnn names the controls when they are rendered to the page. Any suggestions?

Thank you

Mitchel, thanks for the quick response. No I am not validating the field or I would use the delivered asp.net validation controls. I just want to inform the user that a field was left blank and if that is their actual intention. I will try your suggestion and post back tonight..

Mitchel, that worked perfect. I have one more question. How can check the contents of a dnn rich text editor?

I have tried csText.AppendFormat("if (document.getElementById(""{0}"").value=="""")", Me.rteEmailBody.ClientID)

but this generates a javascript error. Do you have any suggestions?

Thank you

I also tried csText.AppendFormat("if (document.getElementById(""{0}"").innerHTML=="""")", Me.rteEmailBody.ClientID) without luck

Thanks Mitchel.... I solved the problem with you recommendation of looking at the markup and a little assistance from google. In case anyone is interested here is the solution below.

Dim cs As ClientScriptManager = Page.ClientScript
            If Not cs.IsClientScriptBlockRegistered(csType, csEmailCheck) Then
                Dim csText As New StringBuilder()
                csText.Append(Environment.NewLine + "[script removed]                 csText.Append(Environment.NewLine + "function CheckEmail(){")
                csText.Append(Environment.NewLine)
                csText.Append(Environment.NewLine + "var answer")
                csText.Append(Environment.NewLine)
                If rteMail.EditMode = DotNetNuke.UI.WebControls.PropertyEditorMode.Edit Then
                    csText.AppendFormat("var oEditor = FCKeditorAPI.GetInstance(""{0}"");", Me.rteMail.ClientID + "edit")
                Else
                    csText.AppendFormat("var oEditor = FCKeditorAPI.GetInstance(""{0}"");", Me.rteMail.ClientID + "view")
                End If
                csText.Append(Environment.NewLine)
                csText.Append(Environment.NewLine + "var pageValue = oEditor.GetXHTML(true);")
                csText.Append(Environment.NewLine)
                csText.AppendFormat("if(document.getElementById(""{0}"").value=="""" && pageValue==""

&#160;

&#160;

Left a part out

csText.Append(Environment.NewLine + "var answer = new Boolean(""true"");")