Using mix-ins to add behavior

We've seen how to use inheritance and composition to add behavior. There is a different method of composition that appends behavior onto existing classes without inheritance. Using mix-ins attaches properties to an object instance at runtime.

In this recipe, we'll see how to use the mix-ins to add shared behavior to classes without inheritance.

Getting ready

This recipe assumes you already have a workspace that allows you to create and run ES modules in your browser. If you don't, please see the first two chapters.

How to do it...

1. Open your command line application and navigate to your workspace.
2. Create a new folder named 08-08-using-mixins.
3. Copy or create an index.html that loads and runs a main function from main.js.

4. Create a main.js file that defines a new class named Rocket. In the constructor, extend the current instance with an object named Launcher:

// main.js 
class Rocket { 
  constructor(name) { 
    Object.assign(this, Launcher); 
    this.name = name; 
 ...