there is no command to get the source of XML nodes. (they are killing XMLSerializer soon)
you MIGHT be able to simply grab the node and append it to your HTML element.
you might need to use
importNode depending on the strictness in use.
otherwise maybe a temp div will work?
Code:
var d=document.createElement("div")
d.appendChild(res.getElementsByTagName("svg")[0]);
alert(d.innerHTML);
or, the worst-case:
Code:
var d=document.createElement("div")
d.innerHTML=res.responseText;
var svg1=d.getElementsByTagName("svg")[0];
alert(svg1.outerHTML);