Question

To define each of the set classes as a property of the sets object (namespace) for the module, the statement is

(a) sets = sets.AbstractEnumerableSet.extend();

(b) sets.SingletonSet = sets.AbstractEnumerableSet.extend(…);

(c) sets.SingletonSet = sets.extend(…);

(d) sets = sets.extend(…);

This question was posed to me during a job interview.

The origin of the question is Modules in JavaScript topic in portion Classes and Modules in JavaScript of JavaScript

Answer 1

The correct answer is (b) sets.SingletonSet = sets.AbstractEnumerableSet.extend(…);

To explain I would say: Singleton is an object which can only be instantiated once. The extend keyword is used in class declarations or class expressions to create a class which is a child of another class. The sets object is the namespace for the module, and we define each of the set classes as a property of this object.