Thanks Greg, its work
can i ask again,
XDocument.DOM.selectSingleNode(''/dfs:myFields/dfs:dataFields/tns:XUmmeldProcessRequest/tns:DocumentPrefs/tns:GUID'').text = Math.random()*1000;
from them I have GUI Random : 7017371754586900
how can i made 7017-3717-5458-6900 ?
my code is :
function XDocument::OnLoad(eventObj){
var Name = ...