javascript无刷新回传问题？

[csover8]

需求是这样的：看js代码。

var AllOrNone = ""

var setclassid = ""

var xmlHttpCheck;
try
{
xmlHttpCheck=new ActiveXObject("Msxml2.XMLHTTP");
}
catch(e)
{
try
{
xmlHttpCheck=new ActiveXObject("Microsoft.XMLHTTP"); //老版本浏览器
}
catch(e)
{
xmlHttpCheck=false;
}
}

if (!xmlHttpCheck && typeof (XMLHttpRequest)!='undefined') //其它浏览器，如FF等...
{
xmlHttpCheck=new XMLHttpRequest();
}


function SetCurrentAll(classid)
{
setclassid = classid;

if(document.getElementById("chkClassid"+classid).checked==true)
{
AllOrNone = true;
}
else
{
AllOrNone = false;
}


if(AllOrNone == true)
{

var urlCheckAll="getboby.asp?classid="+escape(setclassid)+"&r=" + Math.random();

xmlHttpCheckAll.open("Get",urlCheckAll,true);

xmlHttpCheckAll.onreadystatechange=userbacknoteAll;

xmlHttpCheckAll.send(null);



document.getElementById("classid"+classid).className = "aa";
}
else
{
document.getElementById("selectedbabyid"+setclassid).value = "";

document.getElementById("classid"+classid).className = "";
}

}


function userbacknoteAll()
{
if (xmlHttpCheckAll.readyState==4)
{
var response=xmlHttpCheckAll.responseText;

responseSplit = response.split(";");

var currentselectbaby = "";


for(i=0;i<=responseSplit.length-2;i++)
{

strArray = responseSplit[i].split(",");

currentselectbaby = currentselectbaby + "," + strArray[0];

}
//alert(currentselectbaby);

document.getElementById("selectedbabyid"+setclassid).value = currentselectbaby.substring(1);

}
}


有个js中的字符串 a =3102,3251,1256 (说明：a为classid的构造字符串)
现在进行这个字符串的分割后调用上头的函数：

for(var p=0;p<a.length;p++)
{
SetCurrentAll(classidsplit[p]); //这里调用上面的SetCurrentAll

}

这里出错了，只有后头的1256这个有值，其它3102,3251都无值的(数据表里头是有值的)，即是打印出currentselectbaby为空值。为何呢？帮我看一下，谢谢了。

[csover8]

问题查找出来了，现在我想问的是，数据还没有从服务器上返回完成的时候，怎么做？

function userbacknoteAll()
{
if (xmlHttpCheckAll.readyState==4)
{
if(xmlHttpCheckAll.status==200)
{
var response=xmlHttpCheckAll.responseText;

responseSplit = response.split(";");

var currentselectbaby = "";


for(i=0;i <=responseSplit.length-2;i++)
{

strArray = responseSplit[i].split(",");

currentselectbaby = currentselectbaby + "," + strArray[0];

}

document.getElementById("selectedbabyid"+setclassid).value = currentselectbaby.substring(1);

}
else
{
//这里怎么样写，等待数据从服务器回传回来，再执行
}
}