XMLDocument object in Internet Explorer 9 does not contain definition for selectSingleNode Xpath-based traversal anymore.
Of course, I googled a little and came across this thread, where it is unsure is it missing by specification or by the fact it is still "in beta".
Anyone have idea how to resolve this, is there some other way of XPath traversal trough XMLDocument that is "IE9 Way"?
XPath is not available in IE9's native XML support; we recommend moving to the Selectors API instead. If required, XPath support is still available using the MSXML ActiveX objects.
来源：https://stackoverflow.com/questions/3820757/ie9-selectsinglenode-missing-from-beta-how-to-overcome-this-in-javascript