title: ReferenceError: json is not defined when AJAX call the server method
body: <p>I want to call the server method through the AJAX call. But when I am click the button and call the AJAX function at that time it shows an error.</p>
  
  <p>Here is my code</p>
  
  <pre><code>&lt;input type="button" id="btn_findsubmit" value="Edit" class="button" /&gt;
  
  $(document).on("click", "#btn_findsubmit", function (e) {
      var c = $find("&lt;%=cmbobx_search.ClientID %&gt;");
      $.ajax({
          type: "POST",
          url: "schoolregistration.aspx/GetSchoolName",
          data: json.stringify({ schoolname: c.get_textboxcontrol().value }),
          contenttype: "application/json; charset=utf-8",
          datatype: "json",
          success: OnSuccessGetSchoolName,
          failure: function () {
              alert("error! try again...");
          }
      });
  });
  </code></pre>
  
  <p>[WebMethod]
  [ScriptMethod]</p>
  
  <pre><code>public static string GetSchoolName(string schoolName){
     //Here is the code
  }
  </code></pre>
  
  <p>Now when I click the button at that time JavaScript button click event is working but the ajax method do not calling the server method GetSchoolName (I know by doing debug mode).</p>
  
  <p>And throws a error that:</p>
  
  <blockquote>
    <p>ReferenceError: json is not defined</p>
  </blockquote>