https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/call

function Product(name, price) {

  this.name = name;

  this.price = price;

}

function Food(name, price) {

  Product.call(this, name, price);

  this.category = 'food';

}

function Toy(name, price) {

  Product.call(this, name, price);

  this.category = 'toy';

}

var cheese = new Food('feta', 5);

var fun = new Toy('robot', 40);

var animals = [

  { species: 'Lion', name: 'King' },

  { species: 'Whale', name: 'Fail' }

];

for (var i = 0; i < animals.length; i++) {

  (function(i) {

    this.print = function() {

      console.log('#' + i + ' ' + this.species

                  + ': ' + this.name);

    }

    this.print();

  }).call(animals[i], i);

}

function greet() {

  var reply = [this.person, 'Is An Awesome', this.role].join(' ');

  console.log(reply);

}

var i = {

  person: 'Douglas Crockford', role: 'Javascript Developer'

};

greet.call(i); // Douglas Crockford Is An Awesome Javascript Developer