Javascript Ajax Validation - BunksAllowed

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Javascript Ajax Validation

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Content of index.html

<html> <head> <title>Userdetails</title> <script type="text/javascript"> var ajaxRequest = null; // The variable that makes Ajax possible! function validate() { alert("Trying to validate username"); alert("Trying to check whether Ajax can run") try { // Opera 8.0+, Firefox, Safari ajaxRequest = new XMLHttpRequest(); alert("try---1"); } catch (e) { // Internet Explorer Browsers try { ajaxRequest = new ActiveXObject("Msxml2.XMLHTTP"); alert("try---2"); } catch (e) { try { ajaxRequest = new ActiveXObject("Microsoft.XMLHTTP"); alert("try---3"); } catch (e) { // Something went wrong alert("Your browser broke!"); return false; } } } var target = document.getElementById("username"); var url = "ValidateServ?username=" + target.value; alert(url); ajaxRequest.open("GET", url, true); ajaxRequest.send(null); ajaxRequest.onreadystatechange = processRequest; } function processRequest() { if (ajaxRequest.readyState == 4) { alert(ajaxRequest.responseText); var body = document.getElementsByTagName("body")[0]; if (ajaxRequest.status == 200) { if (ajaxRequest.responseText == true) var textNode = document .createTextNode("This username is validated"); else var textNode = document .createTextNode("This username is not validated"); } else { alert("Error"); } domUpdate("%%%%%%"); body.appendChild(textNode); } } function domUpdate(message) { alert(message) } </script> </head> <body> <form name="username"> <input type="text" id="username" name="username" onblur="validate();"> </form> </body> </html>

Content of ValidateServ.java


package com.t4b.ajax.test; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; /** * Servlet implementation class ValidateServ */ @WebServlet("/ValidateServ") public class ValidateServ extends HttpServlet { private static final long serialVersionUID = 1L; /** * @see HttpServlet#HttpServlet() */ public ValidateServ() { super(); // TODO Auto-generated constructor stub } /** * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse * response) */ protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String name = request.getParameter("username"); response.setContentType("text/plain"); response.setHeader("Cache-Control", "no-cache"); if (name.equals("anindita")) response.getWriter().write("true"); else response.getWriter().write("false"); System.out.println("*****************************************"); } /** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse * response) */ protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // TODO Auto-generated method stub } }


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