Using setters to encapsulate values

In the previous recipe, we saw how to prevent values from being written. Sometimes however, we don't want to prevent a property from being written to. Rather, we want to control how it is written to. In this recipe, we'll see how to use set to control the writing of a property.

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 07-06-setters-encapsulate.
3. Copy or create an index.html that loads and runs a main function from main.js.
4. Create a main.js file with a Rocket class that writes a ­_secretName property upon construction:

class Rocket { 
  constructor(name) { 
    this._secretName = name; 
  }  
} 

5. Add a getter and setter for a name property and only update it if the newValue is a string:

class Rocket { 
  // ... 
  get name() {...