• Create a new file, src/dog.js, containing the following ES6 class:

class Dog {
  constructor(name) {
    this.name = name;
  }

  bark() {
    return `Wah wah, I am ${this.name}`;
  }
}

module.exports = Dog;

It should not look surprising to you if you've done OOP in the past in any language. It's relatively recent for JavaScript though. The class is exposed to the outside world via the module.exports assignment.

Typical ES6 code uses classes, const and let, "template strings" (with back ticks) like the one in bark(), and arrow functions ((param) => { console.log('Hi'); }), even though we're not using any in this example.

In src/index.js, write the following:

const Dog = require('./dog');

const toby = new Dog('Toby');

console.log(toby.bark());

As you can see, unlike the NPM-community-made package color that we used before, when we require one of our files, we use ./ in the require().

• Run npm start and it should print 'Wah wah, I am Toby'.

• Take a look at the code generated in lib to see how your compiled code looks like (var instead of const for instance).

Next section: 5 - The ES6 modules syntax

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