Defining methods on a class

Classes that hold values are not particularly interesting. We also want them to be able to have some behaviors that act as interfaces to the outside world. In this recipe, we'll see how to add methods to a class.

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 07-03-defining-methods.
3. Copy or create an index.html that loads and runs a main function from main.js.
4. Create a main.js with a class named Rocket, which assigns a name property upon construction:

// main.js 
class Rocket { 
  constructor(name) { 
    this.name = name; 
  } 
} 

5. Add a method named takeoff that accepts an option countdown argument. The body of the method should log a message before and after a timeout:

// main.js 
class Rocket { 
  // ... 
  takeOff(countdown = 1000) {...