function CreateXMLHttpRequest()//这里是构造XMLHttpRequest对象的方法
{
    var xmlHttpRequest = null;//这里是大家都常用的IE，firefox中取得XMLHttpRequest对象的方法
    try 
    {

        xmlHttpRequest = new XMLHttpRequest(); 
    }
    catch(e)
    {
        try
        {
            xmlHttpRequest=new ActiveXObject("Msxml2.XMLHTTP");
        }
        catch(e)
        {
            xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");

        }
    }

    return xmlHttpRequest;
}

function AjaxSubmit(url,data,changeFunction)//url指定跳转页,data是要post的数据。changeFunction类似于函数指针
{
    var xmlHttpResquest = CreateXMLHttpRequest();
    xmlHttpResquest.open("post",url,true);
    xmlHttpResquest.setRequestHeader("content-length",data.length);
    xmlHttpResquest.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
    xmlHttpResquest.send(data);

    xmlHttpResquest.onreadystatechange = function ()
    {
        if (xmlHttpResquest.readyState == 4)
        {
            try
            {
                if(xmlHttpResquest.status == 200)
                {
                    changeFunction(xmlHttpResquest.responseText);//这里可以调用想要的函数
                }
            }
            catch(e)
            {
                alert("over");
            }
        }
    }

}