原生Ajax

1. var userName;    
2. var passWord;    
3. var xmlHttpRequest;   

//XmlHttpRequest对象    
function createXmlHttpRequest(){    
    if(window.ActiveXObject){ //如果是IE浏览器    
        return new ActiveXObject("Microsoft.XMLHTTP");    
    }else if(window.XMLHttpRequest){ //非IE浏览器    
        return new XMLHttpRequest();    
    }    
}    
    
function onLogin(){    
    userName = document.f1.username.value;    
    passWord = document.f1.password.value;      
    //这个地方，怎么直接调用方法名称也许是原生的缺陷    
    var url = "test.aspx?username="+userName+"&password="+passWord+"";       
            
    //1.创建XMLHttpRequest组建    
    xmlHttpRequest = createXmlHttpRequest();    
        
    //2.设置回调函数    
    xmlHttpRequest.onreadystatechange = zswFun;    
        
    //3.初始化XMLHttpRequest组建    
    xmlHttpRequest.open("POST",url,true);    
        
    //4.发送请求    
    xmlHttpRequest.send(null);      
}       
   
//回调函数    
function zswFun(){    
    if(xmlHttpRequest.readyState == 4 && xmlHttpRequest.status == 200){    
        var b = xmlHttpRequest.responseText;    
        if(b == "true"){    
            alert("登录成功！");    
        }else{    
            alert("登录失败！");    
        }           
    }    
}