Javascript alert not working from code behind

Question

I am generating a javascript alert box from codebehind in asp.net(vb).

The code:

            Catch ex As Exception
                MesgBox(\"Error in up         


        

Answer 1

JavaScript does not allow string constants to span line breaks.

In your server-side code, you're going to have to replace the newlines in the error message with "\n".

Answer 2

Add Imports System.Web.Script.Serialization to the top of your file, then try this:

Private Sub MesgBox(ByVal sMessage As String)
    Dim serializer as New JavaScriptSerializer()
    Dim msgedtble As String = serializer.Serialize(sMessage)
    Page.ClientScript.RegisterStartupScript(Me.GetType, "myScripts",
        "<script type='text/javascript'>alert(" & msgedtble & ");</script>")
End Sub

Using JavaScriptSerializer should take care of the linebreaks, single quotes, and everything else we haven't already thought of.

Answer 3

To carry on with the answer given by Pointy, your message contains ' characters, which you need to escape.

Try this...

  msgedtble = msgedtble.Replace(vbNewLine, "\n").Replace("'","\'")

It is also better to have type='text/javascript' rather than language='javascript'... although this is not absolutely necessary.