An extension to altCognito's point.. Element isn't a defined base type either...
//uses jQuery
function getSomething(input) {
if (typeof(input) == string)
input = $(input)[0] || $('#'+input)[0] || null;
if (input instanceof Element)
input = $(input);
if (input instanceOf jQuery) {
...do something...
}
}
I had to replace the instanceOf Element with..
if (input && input.tagName)...
Would be nice if DOM elements were properly base classed in IE all around.