JS OOP

constructor.js

var ninja = (function(){
 function Ninja(){}
 return new Ninja();
})();

// Make another instance of Ninja
var ninjaB = new ninja.constructor();

assert( ninja.constructor == ninjaB.constructor, "The ninjas come from the same source." );

ineritence.js

function Person(){} 
Person.prototype.dance = function(){}; 
 
function Ninja(){} 
 
// Achieve similar, but non-inheritable, results 
Ninja.prototype = Person.prototype; 
Ninja.prototype = { dance: Person.prototype.dance }; 
 
assert( (new Ninja()) instanceof Person, "Will fail with bad prototype chain." ); 
 
// Only this maintains the prototype chain 
Ninja.prototype = new Person(); 
 
var ninja = new Ninja(); 
assert( ninja instanceof Ninja, "ninja receives functionality from the Ninja prototype" ); 
assert( ninja instanceof Person, "... and the Person prototype" ); 
assert( ninja instanceof Object, "... and the Object prototype" );

oopjs-demo.js

function User(first, last){ 
  if ( !(this instanceof User) ) //if ( !(this instanceof arguments.callee) ) 
    return new User(first, last); 
   
  this.name = first + " " + last; 
} 
 
var name = "Resig"; 
var user = User("John", name); 
 
assert( user, "This was defined correctly, even if it was by mistake." ); 
assert( name == "Resig", "The right name was maintained." );

private.js

// Private properties, using closures.
function Ninja(){ 
  var slices = 0; 
   
  this.getSlices = function(){ 
    return slices; 
  }; 
  this.slice = function(){ 
    slices++; 
  }; 
} 
 
var ninja = new Ninja(); 
ninja.slice(); 
assert( ninja.getSlices() == 1, "We're able to access the internal slice data." ); 
assert( ninja.slices === undefined, "And the private data is inaccessible to us." );