ajax 浏览器支持解决

function xmlHttp()
{
    xmlhttp = false;
    xmlhttpObj = ["MSXML2.XmlHttp.5.0","MSXML2.XmlHttp.4.0","MSXML2.XmlHttp.3.0","MSXML2.XmlHttp","Microsoft.XmlHttp"];
    
    if(window.XMLHttpRequest)
    {
        xmlhttp = new XMLHttpRequest();
    }
    else if(window.ActiveXObject)
    {
        for(i=0;i<xmlhttpObj.length;i++)    
        {
            xmlhttp = new ActiveXObject(xmlhttpObj[i]);
            if(xmlhttp)
            {
                break;    
            }
        }
    }
    else
    {
        alert("暂时不能创建XMLHttpRequest对象");
    }
    return xmlhttp?xmlhttp:false;
}