Question

I have following JavaScript function, Which call Jquery JSON function and get the DateTime with respect to timezone. This works fine.

  <script type="text/javascript">
    function JSFunctionName() {
        $(document).ready(function () {
            var timezone = "US/Central";
            $.getJSON("http://json-time.appspot.com/time.json?tz=" + timezone + "&callback=?",
function (data) {
    if (data.hour < 12) {
        //alert(data.hour + ':' + data.minute); // want to return this value data.hour + data.minute
        //document.getElementById('<%=HiddenField1.ClientID %>').value = data.hour + ':' + data.minute;// this does not work
    }
})
        });
    }
</script>

Now I am calling this Javascription function in Code behind on onclick of button

<asp:Button ID="Button1" runat="server" Text="Button" onclick="Button1_Click" />

Code behind

protected void Button1_Click(object sender, EventArgs e)
{
    Page.ClientScript.RegisterStartupScript(this.GetType(),
        "alert", "JSFunctionName();", true);
    // here I need the DateTime value that is get from JSON
    //Response.Write(HiddenField1.Value); 
}

How can I return the value from Javascript to code behind immediate after call of Page.ClientScript.RegisterStartupScript

Please note I have try to set the value in HiddenField, but its not working. you can see in the comment.

Any idea or alternative solution will be appreciated.

Thanks

Answer 1

You can’t do this without posting back to the server. The reason for this is that javascript executes on the client, and it will only execute after the page has left the server.

I assume this is a contrived example, but in this specific case, if you want to have the same information available on the client and server, you need to compute it on the server, and pass that out to the client.

If this isn’t possible, you’ll need to create a webservice, but that will have to handle the response asynchronously.