Function expressions vs Function declarations

function-declaration.js

// This is a function declaration
function foo(){};

function-expression.js

// This is a function expression
var foo = function(){};

hoisting.js

// Hoisting in practice

bar(); // Returns "bar", because function is hoisted into beginning of scope
function bar(){
  return "bar";
};
bar(); // Still returns "bar"

foo(); // Casts TypeError: undefined is not a function, because the var is hoisted as undefined, but the function isn't.
var foo = function(){
  return "foo";
};
foo(); // Returns "foo"

named-function-expressions.js

var Foo = function(){};
function Bar(){};

var instanceOfFoo = new Foo();
var instanceOfBar = new Bar();

instanceOfFoo.constructor.name; // Returns nothing
instanceOfBar.constructor.name; // Returns "Bar"

// Solution
var Fubar = function Fubar(){};

var instanceOfFubar = new Fubar();

instanceOfFubar.constructor.name; // Returns "Fubar", but beware, might behave unexpectedly in IE<9 - see http://kangax.github.com/nfe/

names-inheritance-right.js

// Naming and inheritance - corrected!

// Base class
var BaseClass = function BaseClass(){
  return this;
};

// Sub class - inherits from BaseClass
var SubClass = function SubClass(){
  return BaseClass.apply(this, arguments); // Use base class constructor
};
SubClass.prototype = new BaseClass(); // This ensures the inheritance
SubClass.prototype.constructor = SubClass; // This corrects the constructor pointer because it points to BaseClass - https://developer.mozilla.org/en/Introduction_to_Object-Oriented_JavaScript#Inheritance

// Instantiate
var instanceSub = new SubClass();

// Get name
instanceSub.constructor.name // Returns "SubClass" - YAY!

names-inheritance-wrong.js

// Naming and inheritance

// Base class
var BaseClass = function BaseClass(){
  return this;
};

// Sub class - inherits from BaseClass
var SubClass = function SubClass(){
  return BaseClass.apply(this, arguments); // Use base class constructor
};
SubClass.prototype = new BaseClass(); // This ensures the inheritance

// Instantiate
var instanceSub = new SubClass();

// Get name
instanceSub.constructor.name // Returns "BaseClass" - WTF?!