Passing Variable from JS to VB.net

Question

I have a variable that gets a value in a js function. I need to get its value as a double into a vb.net variable.

I have tried putting the variable into a label then grabbing it from the label in vb.net as shown in the code below:

Js part.

document.getElementById("Label1").innerText = nwLat;

then in the vb part

   Dim nwLat As Double
    nwLat = Label1.Text
    MsgBox(nwLat)

it does not work for me any ideas? the error that comes up is Input string was not in a correct format.

Cheers!

What isn't working? Does the code throw an Exception? Is the value simply empty? We need more details... — Justin Niessner
– Justin Niessner, Commented Aug 18, 2011 at 15:49
The label's text value will be maintained in and retrieved from ViewState, so this is unlikely to work. Try using an <input type="hidden" /> instead. — Chris Shouts
– Chris Shouts, Commented Aug 18, 2011 at 15:53

cillierscharl · Accepted Answer · 2011-08-18 16:01:18Z

3

Easiest way without any type of ajax would be to use a hidden field.

Markup:

<asp:HiddenField ID="nwLatHidden" runat="server" Value="" />

JS:

document.getElementById('nwLatHidden').value = '6.00'; // or of course the value from your function.

.NET during your postback routine:

Dim nwLat As Double
nwLat = nwLatHidden.Value

edited Aug 18, 2011 at 16:01

answered Aug 18, 2011 at 15:51

cillierscharl

7,1053 gold badges31 silver badges46 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

Sam Over a year ago

it Errors with ~Input string was not in a correct format at nwLat = CDbl(nwLatHidden.value)

Chris Shouts Over a year ago

Do you know how to attach a debugger? What is the value of nwLatHidden before trying to cast it to a double?

cillierscharl Over a year ago

See my edit above and check the result to see if it can be parsed into the double type.

shawndumas · Accepted Answer · 2011-08-18 16:26:26Z

2

In JavaScript:

__doPostBack(
    'edit',
    JSON.stringify({ ID: id, Code: code, AcctNo: acctNo })
);

In VB.NET:

Protected Sub Page_Load(s As Object, e As EventArgs) Handles Me.Load
    If Not Page.IsPostBack Then
        '...
    Else
        Dim eventTarget As String = Request.Form!__EVENTTARGET
        Dim eventArgument As String = Request.Form!__EVENTARGUMENT
        If Not eventArgument Is Nothing AndAlso Not eventTarget Is Nothing AndAlso eventTarget = "edit" Then
            Dim jss As New JavaScriptSerializer()
            Dim ac As AccountCode = jss.Deserialize(Of AccountCode)(eventArgument)
        End If
    End If
End Sub

edited Aug 18, 2011 at 16:26

answered Aug 18, 2011 at 16:16

shawndumas

1,43315 silver badges17 bronze badges

Comments

James Johnson · Accepted Answer · 2011-08-18 15:50:19Z

1

You need to use the ClientID or the UniqueID:

document.getElementById("<%=Label1.UniqueID%>").innerText = "Hi";

answered Aug 18, 2011 at 15:50

James Johnson

46.1k8 gold badges75 silver badges111 bronze badges

Collectives™ on Stack Overflow

Passing Variable from JS to VB.net

3 Answers 3

3 Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

3 Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related