prototype2.js

function Parent () {
  this.arrayInside = [1];
  this.numberInside = 1;
}

Parent.arrayOutside = [2];
Parent.numberOutside = 2;

Parent.prototype.arrayPrototype = [3];
Parent.prototype.numberPrototype = 3;
Parent.prototype.construtor = Parent;

function Child() {
  Parent.call(this);
  this.arrayInside = [4];
  this.numberInside = 4;
}

Child.prototype = Object.create(Parent.prototype);
Child.prototype.constructor = Child;

var parent = new Parent()
var child = new Child()

parent.arrayInside.push(5);
parent.__proto__.arrayPrototype.push(6);
 console.log(parent.arrayOutside);
//why?????
//undefined??
//not [2]
//oh it's not on __prototype__ T_T
 console.log(parent.arrayPrototype);
//[3, 6]
parent.arrayPrototype = [0];
parent.arrayPrototype.push(1);
console.log(parent.arrayPrototype);
//[0, 1]
console.log(child.arrayPrototype);
//[3, 6]