HelloWorld - Ajax, Struts

This is a simple HelloWorld example for Ajax & Struts. In this example, I have a rudimentary Ajax call to the server side Struts Action class.

JavaScript:

<SCRIPT language="javascript">
   var xmlHttp;
   function greet(name) {
       xmlHttp = GetXmlHttpObject();
       if (xmlHttp == null) {
           alert("Critical Browser Error: Pls. close the browser & try again!");
           return false;
       }
       // struts action call
       var url = "sayHello.do";
       url = url + "?name=" + name.value;
       url = url + "&sid=" + Math.random();
       xmlHttp.onreadystatechange = stateChanged;
       xmlHttp.open("GET", url, true);
       xmlHttp.send(null);
   }

   function stateChanged() {

       if (xmlHttp.readyState == 4) {
           if (xmlHttp.status == 200) {
               var strutsResp = xmlHttp.responseText;
               document.getElementById("strutsResp").innerHTML = strutsResp;
           } else {
               alert("Critical Browser Error: Pls. close the browser & try again!");
           }
       }
   }

   function GetXmlHttpObject() {
       var xmlHttp = null;
       try {
           xmlHttp = new XMLHttpRequest();
       } catch (e) {
           try {
               xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
           } catch (e) {
               xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
           }
       }
       return xmlHttp;
   }
</SCRIPT>

HTML Form:

<form><!-- onchange='greet(this);'-->
<p><LABEL for="name">Name: <input type="text" name="name"
   size="10" id="name" onchange='greet(this);'/></LABEL>
<input type="button" id="ok" value="OK"/>
</p>
</form>

Struts Config:

   <!--Note: the response is fully cooked - no mapping required! -->
   <action-mappings>
       <action path="/sayHello" type="com.aj.helloajax.actions.SayHelloAction">
       </action>
   </action-mappings>

Struts Action Class:

public class SayHelloAction extends Action {

   public ActionForward execute(
       ActionMapping mapping,
       ActionForm form,
       HttpServletRequest request,
       HttpServletResponse response)
       throws Exception {

       String name = (String)request.getParameter("name");
       response.setContentType("text/html");
       PrintWriter out = response.getWriter();
      
       out.print("<h2>Hello "+name+" !!</h2>");
       out.flush();
       response.flushBuffer();
       //Note: the response is fully cooked - no mapping required!
       return null;
   }
}