How to create an object of XMLHttpRequest

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);

            if (xmlhttp) {

                break;

            }

        }

    } else {

        alert("暂时不能创建XMLHttpRequest对象");

    }

    return xmlhttp?xmlhttp:false;

}

function createXMLHttpRequest() {

    if (window.ActiveXObject) {

        xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");

    } else if (window.XMLHttpRequest) {

        xmlHttp = new XMLHttpRequest();

    }

}

else if ( window.ActiveXObject ) {

        try {

            xhr = new ActiveXObject("Msxml2.XMLHTTP");

        }

        catch (e) {

            xhr = false;

        }

    }