gistfile1.js

var str = '<data><user id="1" name="Hakan Bilgin">'+
          '<mail>hbi@bredband.net</mail></user></data>',
    doc = Defiant.xmlFromString(str),
    obj = Defiant.node.toJSON(doc.documentElement);

console.log( JSON.stringify(obj, null, '\t') );
/*
{
    "user": {
        "@id": 1,
        "@name": "Hakan Bilgin",
        "mail": "hbi@bredband.net"
    }
}
*/

// Changing it back to XML
var doc2 = JSON.toXML( obj );

console.log( Defiant.node.prettyPrint( doc2 ) );
/*
<?xml version="1.0" encoding="UTF-8"?>
<d:data xmlns:d="defiant-namespace>
    <user id="1" name="Hakan Bilgin">
        <mail>hbi@bredband.net</mail>
    </user>
</d:data>
*/