Constructor, Instance, Composition

prototype.js

/*==============
 * Constructor
 ===============*/

/* function Kitty:
 * prototype: Function
 * __proto__: Object
 */
function Kitty(){
  this.legs = 4;
  this.eyes = 2;
}

Kitty.prototype.lifes = 7;
Kitty.prototype.ears = 2;


/*==============
 * Instance
 ===============*/

/* misifus:
 * prototype: Kitty
 *__proto__: Object
 */
let misifus = new Kitty();

/*==============
 * Composition
 ===============*/
const food = name => ({food: name});

const box = hasOne => ({box: hasOne});

const feed = () => {
  return {
    feed: function(){
      console.log(`Mhhh, ${this.food}`);
    }
  }
}

/* garfield:
 * prototype: Kitty
 *__proto__: Object
 */
let garfield = Object.assign(new Kitty(), food('lasagna'), box(true), feed());
garfield.feed();
console.log(garfield)