简单示例：AJAX结合PHP代码实现登录

javascript:tagshow(event, 'HTML');" href="javascript:;" target=_self>HTML部分：

function postRequest(strURL){
var xmlHttp;
if(window.XMLHttpRequest){ // For Mozilla, Safari, ...
var xmlHttp = new XMLHttpRequest();
}
else if(window.ActiveXObject){ // For
[url=javascript:;]Internet[/url]
Explorer
var xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
}
xmlHttp.open('POST', strURL, true);
xmlHttp.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
xmlHttp.onreadystatechange = function(){
if (xmlHttp.readyState == 4){
updatepage(xmlHttp.responseText);
}
}
xmlHttp.send(strURL);
}
function updatepage(str){
if(str=="yes"){
alert("Welcome User");
}else{
alert("Invalid Login! Please try again!");
}
}
function call_login(){
var username = window.document.f1.username.value;
var password = window.document.f1.password.value;
var url = "login.php?username=" + username + "&password=" +password ;
postRequest(url);
}
Login
User
Name:
Password:

[url=javascript:;]PHP[/url]
脚本部分login.php：