function loadXML(xmlFile) {
    var xmlDoc;
    if (window.ActiveXObject) {
        xmlDoc = new ActiveXObject("Microsoft.XMLDOM");
        xmlDoc.async = false;
        xmlDoc.load(xmlFile);
    }
    else if (document.implementation && document.implementation.createDocument) {
        xmlDoc = document.implementation.createDocument("", "", null);
        xmlDoc.async = false;
        xmlDoc.load(xmlFile);
    } else {
        alert('您的浏览器不支持该系统脚本！');
    }
    return xmlDoc;
}

function init_list(){
    var xmlDoc = loadXML("list.xml");
    if(!xmlDoc){
        alert("load xml false!");
        return false;
    }
    if(-1 != xmlDoc.parseError){ //这个地方会显示有错，提示系统未找到指定对象
        var oError=xmlDoc.parseError;
      alert("error code:"+oError.errorCode+"Line:"+oError.line+"Line Pos:"+oError.linepos+"Reason:"+oError.reason);
    }
    var all = xmlDoc.getElementsByTagName("songs");
    var maxRes = all.length;
    alert("maxRes="+maxRes);//这个地方显示的长度一直是0
}

<?xml version="1.0" encoding="gb2312"?>
<list>
    <songs>
        <name>布拉格广场</name>
    </songs>
</list>

 xmlDoc.load(xmlFile);