<script>    function createAjax(){        var request=false;                //window对象中有XMLHttpRequest存在就是非IE，包括（IE7，IE8）        if(window.XMLHttpRequest){            request=new XMLHttpRequest();            if(request.overrideMimeType){                request.overrideMimeType("text/xml");            }                //window对象中有ActiveXObject属性存在就是IE        }else if(window.ActiveXObject){                        var versions=[‘Microsoft.XMLHTTP‘, ‘MSXML.XMLHTTP‘, ‘Msxml2.XMLHTTP.7.0‘,‘Msxml2.XMLHTTP.6.0‘,‘Msxml2.XMLHTTP.5.0‘, ‘Msxml2.XMLHTTP.4.0‘, ‘MSXML2.XMLHTTP.3.0‘, ‘MSXML2.XMLHTTP‘];            for(var i=0; i<versions.length; i++){                    try{                        request=new ActiveXObject(versions[i]);                        if(request){                            return request;                        }                    }catch(e){                        request=false;                    }            }        }        return request;    }var ajax=createAjax();alert(ajax);</script>