<script type="text/javascript">

        //封装通用的xhr对象，兼容各个版本

        function createXHR(){

            //判断浏览器是否将XMLHttpRequest作为本地对象实现，针对IE7，firefox,opera等

            if(typeof XMLHttpRequest!="undefined"){

                return new XMLHttpRequest();

            }else if(typeof ActiveXObject != "undefined"){

                // 将所有可能出现的ActiveXObject版本放在一个数组中

                var xhrArr=['Microsoft.XMLHTTP','MSXML2.XMLHTTP.6.0','MSXML2.XMLHTTP.5.0','MSXML2.XMLHTTP.4.0','MSXML2.XMLHTTP.3.0','MSXML2.XMLHTTP.2.0'];

                //遍历创建XMLHttpRequest对象

                var len= xhrArr.length , xhr;

                for(var i=0;i<len;i++){

                    try{

                        //创建XMLHttpRequest对象

                        xhr=new ActiveXObject(xhrArr[i]);

                        break;

                    }

                    catch(ex){

                    }

                }

            }else{

                throw new Error('No XHR object available.');

            }

        }

        var xhr=createXHR();

        console.log('xhr');

    </script>