javascript在firefox上创建xml文件的有关问题 _JavaScript

javascript在firefox下创建xml文件的问题
一、如何在firefox文件下写一个xml文件
如何实现以下xml文档
<Steel-ERP><Head sid="899898132932"/><Client job="new" file="1222" file1="eeee"></Client></Steel-ERP>

var oXmlDom = document.implementation.createDocument("","",null);
var oRoot = oXmlDom.documentElement;
var myChildren = oRoot.firstChild ;
var testnode = document.createElement("Steel-ERP");//根节点
myChildren.appendChild(testnode);
为何这样写不行呢？？请高人指证

------解决方案--------------------

HTML code


<script>
window.onload=function(){
    var oXmlDom = document.implementation.createDocument("","Steel-ERP",null); 
    var oRoot = oXmlDom.documentElement; 
    var xs = new  XMLSerializer();
    var node = document.implementation.createDocument("","Head",null).documentElement;
    node.setAttribute("sid","899898132932");
    oRoot.appendChild(node);
    var node = document.implementation.createDocument("","Client",null).documentElement;
    node.setAttribute("job","new");
    node.setAttribute("file","1222");
    node.setAttribute("file1","eeee");
    oRoot.appendChild(node);
    alert(xs.serializeToString( oRoot ));    
}
</script>