JS delegation

greeter-es5-constructor-function.js

/**
 *  Simulate classical ineritance (not recommended) using constructor function
 */

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');

var msg = george.hello();

console.log(msg); // Hello, my name is George

greeter-es6-class.js

/**
 *  Classical ineritance, not recommended
 */

class Greeter {
  constructor (name) {
    this.name = name || 'John Doe';
  }
  hello () {
    return `Hello, my name is ${ this.name }`;
  }
}

const george = new Greeter('George');

const msg = george.hello();

console.log(msg); // Hello, my name is George

greeter-factory-function.js

const proto = {
  hello () {
    return `Hello, my name is ${ this.name }`;
  }
};

const greeter = (name) => Object.assign(Object.create(proto), {
  name
});

const george = greeter('george');

const msg = george.hello();

console.log(msg);