xmlhttp在非IE8浏览器里一闪而过，请问有怎么解决？

xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
var xmrq=new XMLHttpRequest;

这几种方法都试了不行

var xhr = function () {
        try { return new XMLHttpRequest(); } catch (e) {
            try { return new ActiveXObject('Microsoft.XMLHTTP'); } catch (e) {
                try { return new ActiveXObject('Msxml2.XMLHTTP'); } catch (e) { }
            }
        };
    }();