JS CLASSESChapter 5 · JS Functions and Classes

Class Inheritance

class Comet extends SpaceObject creates a class that inherits every method of SpaceObject. In the child's constructor, call super(...) before you use this. Override a method by defining it again, and reach the parent's version with super.method(). instanceof checks the whole chain of parents.

Worked example

How it reads

extends sets up the parent class
super(name) runs the parent constructor first
super.describe() calls the version the child is overriding

Common mistakes

Using this in a child constructor before calling super() throws a ReferenceError.

Cloud tip: Keep inheritance shallow. One or two levels is easy to follow; five is a maze.