code-reuse-patterns/prototypal-inheritance.html

﻿<!doctype html>
<html lang="en">
<head>
<title>JavaScript Patterns</title>
<meta charset="utf-8">
</head>
<body>
<script>
/* Title: Prototypal Inheritance
   Description: objects inherit from other objects
*/

function object(o) {
  function F() {}
  F.prototype = o;
  return new F();
}

// object to inherit from
var parent = {
  name: "Papa"
};

// the new object
var child = object(parent);

// testing 
alert(child.name); // "Papa"


// parent constructor
function Person() {
  // an "own" property
  this.name = "Adam";
}
// a property added to the prototype
Person.prototype.getName = function () {
  return this.name;
};
// create a new person
var papa = new Person();
// inherit
var kid = object(papa);
// test that both the own property
// and the prototype property were inherited
kid.getName(); // "Adam"


// parent constructor
function Person() {
  // an "own" property
  this.name = "Adam";
}
// a property added to the prototype
Person.prototype.getName = function () {
  return this.name;
};
// inherit
var kid = object(Person.prototype);
typeof kid.getName; // "function", because it was in the prototype
typeof kid.name; // "undefined", because only the prototype was inherited


/* Addition to ECMAScript 5 */
var child = Object.create(parent);

var child = Object.create(parent, {
age: { value: 2 } // ECMA5 descriptor
});
child.hasOwnProperty("age"); // true
</script>
</body>
</html>