获取页面iframe中xml节点的文本内容

function fnGetCode(iframeId){
                var obj=null;
                if (document.all){//IE
                    obj = document.frames[iframeId].document;
                    return($(obj).find(“.tx”).text());
                }else{//Firefox
                    obj = document.getElementById(iframeId).contentDocument;
                    return($(obj).find(“code”).text());
                }
            }