Inheriting from a Class: extends keyword and Prototype Chaining

extends implies prototypal inheritance

Even though JavaScript uses the extends keyword, which is popular for inheritance in Java, it’s important to remember that the inheritance is prototype-based and not class-based. Let’s verify this key design for inheritance in JavaScript with an example.

Example

We’ll continue with the Person and ReputablePerson classes we used in the previous lesson. We can obtain the prototype of an object using the Reflect.getPrototypeOf() method. Since prototypes form a chain, we can repeatedly or recursively use this method to walk the inheritance hierarchy—that is, the prototype chain.

Let’s write a function that will print a given object, and then print the object’s prototype chain.