Summary

Throughout this chapter, we discussed how creational design patterns allow us to build more extensible and maintainable systems in JavaScript.

The prototype design pattern shines when creating many instances of objects that contain the same values. This design pattern allows us to change the initial values of the prototype and affect all the cloned instances.

The singleton design pattern is useful to completely hide initialization details of a class that should really only be instantiated once. We saw how JavaScript’s module system generates singletons and how that can be leveraged to simplify a singleton implementation.

The factory method design pattern allows a base class to defer the implementation of some object creations to subclasses. We saw which features would make this pattern more useful in JavaScript, as well as an alternative idiomatic JavaScript approach with factory functions.

We can now leverage creational design patterns to build classes that are composable and can be evolved as necessary to cover different use cases.

Now that we know how to create objects efficiently with creational design patterns, in the next chapter, we’ll cover how to use structural design patterns to organize relationships between different objects and classes.