Introduction

This article is intended for those with a basic understanding of ASP.Net Server Controls and JavaScript.
The agenda is simple; we will learn:
  1. How to do an explicit post-back using JavaScript.
  2. Handle those events on the server-side.
  3. Pass data to the server.
  4. Convert a JSON-formatted string to an object of the specified type.
To fulfill the requirements a "_doPostBack ()" function is used to make the server-side event call. For example, if you want to raise the button (server-side control) click event from the JavaScript then the _doPostBack () function can be used.
Let's go through with one simple and short example to see how this happens.
Default.aspx
  1. <%@ Page Language="C#" AutoEventWireup="false" CodeFile="Default.aspx.cs" Inherits="_Default" EnableEventValidation ="false" %>
  3. <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
  4. <html xmlns="http://www.w3.org/1999/xhtml">
  5. <head runat="server">
  6. <title></title>
  7. <script src="jquery-1.3.2.min.js" type="text/javascript"></script>
  8. <script src="MyJsFile.js" type="text/javascript"></script>
  10. <style type ="text/css">
  11. .ButtonStyle
  12. {
  13. width:15em;
  14. height:2em;
  15. }
  16. </style>
  17. </head>
  18. <body>
  20. <form id="form1" runat="server">
  21. <asp:ScriptManager ID ="ScriptManager1" runat ="server"></asp:ScriptManager>
  22. <div>
  23. <button type ="button" id ="BtnClientSideButton" class ="ButtonStyle" onclick ="funCallServerControl()">Call Server Control</button>
  25. <asp:Button ID ="BtnServerControl" runat ="server" style ="display:none;" />
  26. <asp:Label runat ="server" ID ="Lable1" Text ="" ForeColor="Green" Visible="false"></asp:Label>
  27. </div>
  28. </form>
  29. </body>
  30. </html>
Default.aspx.cs
  1. using System;
  2. using System.Collections.Generic;
  3. using System.Linq;
  4. using System.Web;
  5. using System.Web.UI;
  6. using System.Web.UI.WebControls;
  7. using System.Web.Script.Serialization;
  8. public partial class _Default : System.Web.UI.Page
  9. {
  10. protected void Page_Load(object sender, EventArgs e)
  11. {
  13. }
  14. protected void BtnServerControl_Click(object sender, EventArgs e)
  15. {
  16. JavaScriptSerializer ObjLocSerializer = new JavaScriptSerializer();
  18. List<ClsStorageBO> ObjLocDataStorageBO = ObjLocSerializer.Deserialize<List<ClsStorageBO>>(Request.Form["__EVENTARGUMENT"]);
  19. Lable1.Visible = true;
  20. Lable1.Text = ObjLocDataStorageBO[0].ProPubMessage;
  22. }
  23. }

Summary

In the above-given example, I have used two buttons and one label out of which one is the client-side button and another is the server control. On the click of the client-side button, I have called the JavaScript function in which I'm calling the doPostBack function explicitly to make the server-side control called and also am passing the data in the JSON format. At the server-side I have used the JavaScriptSerializer to convert a JSON-formatted string to an object of the specified type and have assigned it to Lable1 and displayed it.