Classes-like objects example (you shoud use classes, of course!)

object-classes.js

var Foo = {
  construct(who){
    this.me = who;
    this.species = 'fufel';
    return this;
  },
  identify(){
    return 'I am ' + this.me;
  }
}

// class extends Foo
var Bar = Object.assign( Object.create(Foo), {
  construct(who){
    // super(..)
    Foo.construct.call(this, who);
    this.subtype = 'barashek';
    return this;
  },
  speak(){
    console.log('Hello, ' + this.identify());
  }
});

a1 = Object.create(Foo).construct('a1');
b1 = Object.create(Bar).construct('b1');
console.log(a1);
console.log(b1);