Calling vb.net function from javascript

Question

what I want to do is call a vb.net function from javascript
here is my html code.

<html xmlns="http://www.w3.org/1999/xhtml">

<head>
    <title>Untitled
        Page
    </title>
    <script
    src="jquery.js"></script>
        <script
        type="text/javascript">
            $(function(){
            $("button").click(showVbHelloWorld)
            function
            showVbHelloWorld()
            {
            window.external.showVbHelloWorld();
            }
            })

            </script>
</head>

<body>
    <button>A</button>

</body>

</html>

and here is my vb.net code

Imports System
Imports System.Windows.Forms
Imports System.Security.Permissions

<PermissionSet(SecurityAction.Demand, Name:="FullTrust")> 

<System.Runtime.InteropServices.ComVisibleAttribute(True)>

<Microsoft.VisualBasic.ComClass()> 

Public Class Form1

Private Sub Button1_Click(ByVal sender As System.Object, _

        ByVal e As System.EventArgs) Handles Button1.Click

    Me.WebBrowser1.ObjectForScripting = Me

End Sub

Public Sub showVbHelloWorld()

    MsgBox("Hello")

End Sub

End Class

still on button click im geting error
Uncaught TypeError: Object # has no method 'showVbHelloWorld'

sorry for my uneven formatting of the code...i am new to stackoverflow...

Why are you using Javascript. Why not just use .NET event handling???? — adaam
– adaam, Commented Jun 15, 2013 at 11:01
im basically working on javascript...but i want to convert some of my html content to pdf using HiQpdf hiqpdf.com/demo/ConvertHtmlToPdf.aspx and HiQpdf provides c# and vb.net codes thats why i am trying this way... — Krunal Shah
– Krunal Shah, Commented Jun 15, 2013 at 11:05

Steve · Accepted Answer · 2013-10-01 14:37:49Z

Here is a link that shows how to do it: Call VB method from JavaScript

It basically says there are 2 ways, Ajax or Postback. Here is the postback method:

aspx file:

<script type="text/javascript">
 <!--
 function callServersideFunction()
 {
  var someValueToPass = 'Hello server';

 __doPostBack('CustomPostBack', someValueToPass);
 }
 // -->
 </script>

aspx.vb file:

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
  ' Insure that the __doPostBack() JavaScript method is created...
  Me.ClientScript.GetPostBackEventReference(Me, String.Empty)


 If Me.IsPostBack Then
   Dim eventTarget As String
   Dim eventArgument As String

  If ( (Me.Request("__EVENTTARGET") Is Nothing)
    eventTarget = String.Empty
   Else
    eventTarget = Me.Request("__EVENTTARGET"))
   If ( (Me.Request("__EVENTARGUMENT") Is Nothing)
    eventArgument = String.Empty
   Else
    eventArgument = Me.Request("__EVENTARGUMENT"))

  If eventTarget = "CustomPostBack" Then
    Dim valuePassed As String = eventArgument
    ' Call your VB method here...
   End If
  End If
 End Sub

mikefrey · Accepted Answer · 2016-03-09 14:47:27Z

1

you have to put this statement

Me.WebBrowser1.ObjectForScripting = Me

inside form_load

Private Sub form1_Load(sender As Object, e As System.EventArgs) Handles Me.Load
    Me.WebBrowser1.ObjectForScripting = Me
End Sub

see this site:- http://www.codeproject.com/Articles/35373/VB-NET-C-and-JavaScript-communication

edited Mar 9, 2016 at 14:47

mikefrey

4,7013 gold badges32 silver badges41 bronze badges

answered Mar 9, 2016 at 11:35

user3834074

111 bronze badge

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