ajax创建对象

<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>