I\'m trying to shim Element.prototype.children which should return a HTMLCollection
There is a window.HTMLCollection
However
var h = new HTML
Don't expect host objects to behave like (ECMAScript) native objects, they are completely different things. Some browsers do implement their DOM objects like ECMAScript objects, but it is not required and should not be relied upon. Note that most HTML collections are live, it is very difficult to emulate that in a native object.