Not sure I follow this example.
To add things you use a Union operation:
var union = new Union(foo,bar);
or you can
var union = new Union();
union.add(foo);
union.add(bar);
To subtract you use a Subtraction operation:
var subtract = new Subtraction(foo,bar);
So the constructor methods are equal so perhaps your talking about chaining them together. In the union case it makes sense to union n objects together hence we have a .add() method. For subtract it's not clear what subtracting 3 things would do. if its a,b,c is that (a - b) - c?
I could conceive of a general boolean class that did something like this:
var bool = new Boolean().
bool.union(a,b);
bool.subtract(c);
bool.union(d).
This would be (a+b) - c + d.
Is this the type of style your wanting?