How can I check the class of an object in Node 7.10 (ES6)

I'd like to check the class of an object, such as this:

class Foo {}
var foo = new Foo();

I saw this post In ES6, how do you check the class of an object? that correctly says I can use

if (foo instanceof Foo) { ... }

Is there a way to do this without having to require every class I want to check for into the file? If I am doing it with foo instanceof Foo, for lots of classes, I have to require each one into the file (often for only that purpose).

Is there another way?

via Sir Robert