| Ajax Examples |
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AjaxUserNameAvailability.html
<!DOCTYPE HTML PUBLIC “-//W3C//DTD HTML 4.01 Transitional//EN”>
<html>
<head>
<title>AJAX and Servlet</title>
<script language=”javascript”>
var xmlHttp;
function checkUserExist() {
var username = document.getElementById(“username”).value;
var url = “/Ajax/AJAXCheckUserServlet?username=” + username;
if(window.XMLHttpRequest){
xmlHttp = new XMLHttpRequest();
}
else if(window.ActiveXObject){
xmlHttp = new ActiveXObject(“Microsoft.XMLHTTP”);
}
xmlHttp.open(“Get”,url,true);
xmlHttp.onreadystatechange = callback;
xmlHttp.send(null);
}
function callback() {
if( xmlHttp.readyState==4 ){
if( xmlHttp.status==200 ) {
document.getElementById(‘text’).innerHTML = “<br/><b>”+xmlHttp.responseText+”</
b>”;
}
}
}
function focusIn(){
document.getElementById(“username”).focus( );
}
</script>
</head>
<body onload=”focusIn();”>
<form>
User Name <input type=”text” id=”username” name=”username” />
<input type=”button” value=”Check User Name Availability” onClick=”checkUserExist()”/>
<div id=” text” ></div>
</form>
</body>
</html>
Traditionally, when the user registers itself to create the account with the application, there may be
many fields to be entered in addition to the user name. Now the whole data is submitted to the
server. If the user name with the same name exists already then application sends back the same
page again to let the user choose any other user name.
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Apr 2008 | Java Jazz Up | 21 |
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