Javascript：查看从外部源检索的XML

Ok, this piece of code:

好的，这段代码：

    http_request = false;
    http_request = new XMLHttpRequest();
    if (http_request.overrideMimeType) {
        http_request.overrideMimeType('text/xml');
    }
    if (!http_request){return false;}
    http_request.open('GET', realXmlUrl, true);
    http_request.send(null);
    xmlDoc = http_request.responseXML;
    http_r