// 复杂方法，添加了很多检测，和错误处理
var xmlhttp,alerted
try {
    xmlhttp = new ActiveXObject("Msxml2.XMLHTTP")
} catch (e) {
try {
    xmlhttp = new ActiveXObject("Microsoft.XMLHTTP")
} catch (E) {
    alert("请安装Microsofts XML parsers");
}
}
if (!xmlhttp && !alerted){
try {
    xmlhttp = new XMLHttpRequest();
} catch (e) {
    alert("你的浏览器不支持XMLHttpRequest对象，请升级");
}
}
function getClock(){
    var UserName = document.getElementById("UserName").value;
	var Password = document.getElementById("Password").value;
	var ValideCode = document.getElementById("ValideCode").value;
    if (xmlhttp){
        xmlhttp.Open("Get","UserLogin.asp?UserName=" + UserName + "&Password=" + Password + "&ValideCode=" + ValideCode,true);
        xmlhttp.onreadystatechange = RSchange;
        xmlhttp.send();
    }
}

function RSchange(){
    if (xmlhttp.readyState == 1){
        //alert("检测中，请稍候...");
    }
	if (xmlhttp.readyState == 4){
		var returnvalue = xmlhttp.responseText;
        if (returnvalue == "UserNameNull"){
		    alert("用户名为 <A-Z a-z 0-9 _ - .> 6-15个字符之间，注意不要使用空格！");
			document.getElementById("UserName").focus();
		}
    }
	if (xmlhttp.readyState == 4){
		var returnvalue = xmlhttp.responseText;
        if (returnvalue == "UserNameBe"){
		    alert("该帐号名不存在，请重新输入！");
			document.getElementById("UserName").focus();
		}
    }
    if (xmlhttp.readyState == 4){
        var returnvalue = xmlhttp.responseText;
        if(returnvalue == "PasswordError"){
            alert("密码校验错误，请重新输入！");
			document.getElementById("Password").focus();
        }
    }
	if (xmlhttp.readyState == 4){
	    var returnvalue = xmlhttp.responseText;
        if(returnvalue == "ValideCodeError"){
            alert("验证码检验有误，请重新输入！");
			document.getElementById("ValideCode").focus();
        }
    }
}