Introduction

JavaScript Object Notation is an open standard format that uses human-readable text to transmit data objects consisting of attribute-value pairs. It is used primarily to transmit data between a server and web application, as an alternative to XML.
Uses
  1. JSON is a lightweight data-interchange format.
  2. JSON is language independent
  3. JSON is "self-describing" and easy to understand.
Syntax
In client-side.
  1. function <FUNCTION NAME> (<PARAMETER OPTIONAL>) {
  3. $.ajax({
  5. type: <GET/POST>,
  6. contentType: "application/json; charset=utf-8",
  8. url: <TARGET URL>\<SERVER SIDE METHOF NAME>,
  10. data: JSON.stringify({ <PARAMETER TO SEND>: <VALUE> }),
  11. async: <true/false>,
  12. dataType: "json",
  14. success: function (data) {<TO DO>
  15. returnflag = true;
  16. },
  18. error: function (result) {
  19. returnflag = null;
  20. }
  21. });
  23. }
Server side:
  1. [WebMethod]
  2. public static string <SERVER SIDE METHOF NAME> (<PARAMETER>)
  3. {
  4. ….
  5. …
  7. Return XYZ;;
  8. }
Example:
The scenario is we need to get the student name based on the register number.
  1. <asp:TextBox Width="80px" MaxLength="32" ID="txtRegnum" runat="server"onblur="getName();" ></asp:TextBox>
  2. <asp:Label ID="lblStudentName" runat="server" ></asp:Label>
  1. function getName() {
  2. var regNum = '';
  3. var returnflag;
  5. regNum = document.getElementById('txtRegnum').value;
  7. if (regNum != '') {
  8. $.ajax({
  10. type: "POST",
  11. contentType: "application/json; charset=utf-8",
  12. url: "default.aspx/getStudentName",
  13. data: JSON.stringify({ RegNum: regNum }),
  14. async: false,
  15. dataType: "json",
  17. success: function (data) {
  19. if (data.d == '') {
  20. document.getElementById('lblStudentName').innerHTML = '';
  21. }
  22. document.getElementById('lblStudentName').innerHTML = data.d;
  23. returnflag = true;
  24. },
  26. error: function (result) {
  27. returnflag = null;
  28. }
  29. });
  30. }
  31. }
  1. [WebMethod]
  2. public static string getStudentName (string RegNum )
  3. {
  4. ….
  5. …
  7. Return XYZ;;
  8. }