Error handling in AJAX

Thu Aug 23, 2012 1:04 am

In AJAX you use XMLHttpRequest object and waits for readyState, in case of error state is 4:

Code:: if(request) { //The autocalled funtion when the status changed request.onreadystatechange = function() { //Status cases of the readState varrible if(request.readyState==0) document.getElementById('status').innerHTML='Uninitialized'; else if(request.readyState==1) document.getElementById('status').innerHTML='Loading...'; else if(request.readyState==2) document.getElementById('status').innerHTML='Loaded'; else if(request.readyState==3) document.getElementById('status').innerHTML='Interactive'; else if(request.readyState==4) { document.getElementById('status').innerHTML='Completed'; var xml_response = request.responseXML; xml_response.loadXML(request.responseText); var myname=xml_response.getElementsByTagName('name'); document.getElementById('Txtdata').value=myname[0].childNodes[0].nodeValue; }

in case of using DOJO toolkit error code is 500

Code:: dojo.xhrPost( { url: 'service URL', content: {}, handleAs: 'text', load: function(response, ioArgs) { // Do something }, error: function(response, ioArgs) { alert("Failed while doing the operation: " + ioArgs.xhr.response); } });

If you are connecting to a web-server which runs a Servelt and wants to return error for ajax code at client side you can set exception as follows :

Code:: public class siteServelt extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { try { // Your code site here. } catch (Exception exception) { response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR); response.getWriter().write(exception.getMessage()); response.flushBuffer(); } finally { } } }