如何从JavaScript代码向VB.NET方法发送参数？

Question

I have vb.net method and i call it from JS code i can't send parameter to this method and here is sample: JS Code :

function OnSave() 
    {
        var sign = document.FORM1.SigPlus1.Signature();
        <%Save(sign) %>
    }

VB method :

Public Sub Save(ByVal obj As Object)
    Dim obj1 As New PFSIGNATURELib.SigniShellSignature
    obj1.SignatureBytes = obj
    obj1.SaveBitmapToFile(CurDir() & "\sign1.bmp", 200, 200)
    signImg.Src = CurDir() & "\sign1.bmp"

End Sub

Answer 1

Well actually you can do it in an "easy" way:

Add a hidden LinkButton to you page:

<asp:LinkButton runat="server" id="MyPostBackHelper" style="display: none;" />

then in your javascript:

function OnSave() 
{
    var sign = document.FORM1.SigPlus1.Signature();
    __doPostBack(<%= MyPostBackHelper.UniqueID %>, sign);
}

and then in the codebehind:

Public Sub MyPostBackHelper_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles MyPostBackHelper.Click
  Dim obj1 As New PFSIGNATURELib.SigniShellSignature
  obj1.SignatureBytes = Request.Form("__EVENTARGUMENT")
  obj1.SaveBitmapToFile(CurDir() & "\sign1.bmp", 200, 200)
  signImg.Src = CurDir() & "\sign1.bmp"
End Sub

Answer 2

There is no easy way to do it.

Your best bet is to create a web service call, and have Javascript call the web service using ASP.NET Ajax.

Here is a way to do that.

Answer 3

Is it possible to do something like

<%Save(%>sign<%) %> ?

Answer 4

Could you not use the ajax libraries built into .net 3.5 and mark your method as a web Method

       <WebMethod()> _
    Public Shared Function SaveParamsData
End sub

Then use javascript to call that method.

PageMethods.SaveParamsData(ReportItemPramName, MyMethod_Result);

Answer 5

hmm, could you not cause the javascript to post the data back to the page. then check to see if there is postdata on page load, if there is, then save it