js-proto.js

function Parent () {
  this.name = 'Roger'
}

Parent.prototype.yell = function yell () {
  var parent = this
  console.log('My name is ' + parent.name + '!!')
  return parent
}

function Child (name) {
  var child = this

  Parent.call(child)
  // Parent.apply(this, arugments)
  // ^ That would pass along arguments as well

  // After calling the parent construction function,
  // this.name is now set to 'Roger'
  child.parent = child.name
  child.name = name
}

// prototype is the meta object that is assigned to __proto__ on new.
// __proto__ is the meta object of an object used for secondary lookup.
// Good practice to make sure the constructor is set properly.
Child.prototype.__proto__ = Parent.prototype
Child.prototype.constructor = Child

// Set a member method
Child.prototype.talk = function talk () {
  // It is good practice to assign this to a variable.
  // It allows you to avoid lots of context problems later on.
  var child = this

  console.log('My name is ' + child.name + '. My parent is ' + child.parent)
  return child
}

// ====
// Test it.

var child = new Child('Charlie')
child.yell()
child.talk()
console.log(child.__proto__ === Child.prototype)
console.log(child.__proto__.__proto__ === Parent.prototype)

stdout.txt

My name is Charlie!!
My name is Charlie. My parent is Roger
true
true