composition.js

const barker = (state) => ({
  bark: () => console.log('Woof, I am ' + state.name)
})
const driver = (state) => ({
  drive: () => state.position = state.position + state.speed
})
const killer = (state) => ({
  kill: (enemy) => console.log('I killed ' + enemy)
})


const murderRobotDog = (name)  => {
  let state = {
    name,
    speed: 100,
    position: 0
  }
  return Object.assign(
        {},
        barker(state),
        driver(state),
        killer(state)
    )
}

const bruno =  murderRobotDog('bruno')
bruno.bark() // "Woof, I am Bruno"
bruno.kill('Lady Gaga') // "I killed Lady Gaga"

inheritance_bad.js

function Greeter(name) {
  this.name = name || 'John Doe';
}

Greeter.prototype.hello = function hello() {
  return 'Hello, my name is ' + this.name;
}

var george = new Greeter('George');

inheritance_good.js

var proto = {
  hello: function hello() {
    return 'Hello, my name is ' + this.name;
  }
};

var george = Object.create(proto);
george.name = 'George';