ajax

var xmlHttpRequest ;

function validate(){
if(window.ActiveXObject){
try{
xmlHttpRequest =new ActiveXObject("Microsoft.XMLHTTP");
}catch(e){
try{
xmlHttpRequest =new ActiveXObject("Msxml2.XMLHTTP");
}catch(e){}
}

}else if(window.XMLHttpRequest){
xmlHttpRequest =new XMLHttpRequest();
}


if(xmlHttpRequest!=null){
var user_name=$("#user_name").val();
xmlHttpRequest.open("POST","/soft/AjaxServlet?user_name="+user_name,true);
xmlHttpRequest.onreadystatechange=ajaxCallback;
xmlHttpRequest.send(null);
}
}


function ajaxCallback(){
if(xmlHttpRequest.readyState==4){
if(xmlHttpRequest.status==200){
var text=xmlHttpRequest.responseText;
if("The user name has been registered"==text){
$("#msg_name").css("color","red").html("该用户名已被注册");
}else if("You can use the user name"==text){
$("#msg_name").css("color","red").html("您可以使用该用户名");
}else{
$("#msg_name").css("color","red").html(text);
}
}
}
}