Rediscovering JavaScript

Wrapping Up

Metaprogramming is an advanced concept that provides the ability to extend a program at runtime. It is used extensively by libraries and frameworks, but you can also cautiously use it to extend third-party classes in order to make code fluent, less noisy, and easier to use. Member injection is useful to add a known method, field, or property into a class without inheriting from it. To add a method to a class, inject it into the class’s prototype. To inject properties, use the defineProperty() or defineProperties() method.

Exercises

The following exercises will help you strengthen your metaprogramming skills to query objects and inject members. You can find answers to these exerciseshere.

Exercise 1

Complete the following code to print ...