simple $X

dollarX.js

// Simple $X
// Thx! $X from http://coderepos.org/share/browser/lang/javascript/userscripts/jautopagerize.user.js
//              http://subtech.g.hatena.ne.jp/cho45/20071114/1195017746
function $X (exp, context) {
	context || (context = document);
	var exp = (context.ownerDocument || context).createExpression(exp, function (prefix) {
		return (document.createNSResolver((context.ownerDocument == null
			? context : context.ownerDocument).documentElement)
			.lookupNamespaceURI(prefix) || document.documentElement.namespaceURI);
	});
	var result = exp.evaluate(context, XPathResult.ANY_TYPE, null);
	switch (result.resultType) {
		case XPathResult.STRING_TYPE : return result.stringValue;
		case XPathResult.NUMBER_TYPE : return result.numberValue;
		case XPathResult.BOOLEAN_TYPE: return result.booleanValue;
		case XPathResult.UNORDERED_NODE_ITERATOR_TYPE: {
			// not ensure the order.
			var ret = [];
			var i = null;
			while (i = result.iterateNext()) {
				ret.push(i);
			}
			return ret;
		}
	}
	return null;
}