In JavaScript, binding is always explicit, and can be easily lost, so a method using “this” will not refer to the proper object in all situations,  unless you force it to. JavaScript provides two options to do explicit binding “apply” and “call”.

Apply

Every JavaScript function is equipped with “apply” method that allows you to call the function with specific binding. I takes two arguments, the binding object and an array of arguments to be passed to the function.

fun.apply(thisArg[, argsArray])

Call

“Call” method is similar to “apply”, but it takes the arguments themselves not an array.

fun.call(thisArg[, arg1[, arg2[, ...]]])

References

• http://www.alistapart.com/articles/getoutbindingsituations
• https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/Function/apply
• https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/Function/call
• http://stackoverflow.com/questions/962033/what-underlies-this-javascript-idiom-var-self-this

JavaScript event delegation is a simple technique by which you add a single event handler to a parent element in order to avoid having to add event handlers to multiple child elements.

Event capturing

Netscape defined an approach called event capturing, where events occur on the highest object in the DOM tree and then work down to the deepest element affected by the event.

Event bubbling

IE defined event bubbling. The deepest element affected by the event should receive the event first , then its parent, etc., until the document object finally receives the event.

W3C DOM level 2 events specification defines both event bubbling and capturing. First the document receives the event, then the capturing phase commences to the most specific element affected by the event. Once the event is handled by the element, it bubbles back up to the document.

Advantages

• Less event handlers to setup and reside in memory.
• No need to re-attach handlers after a DOM update.

References:

• http://www.nczonline.net/blog/2009/06/30/event-delegation-in-javascript/
• http://www.sitepoint.com/javascript-event-delegation-is-easier-than-you-think/

Public

The members of an object are all public members. There are two ways for putting members in a new object.

In Constructor

function Container(param) {
    this.member = param;
}

In the prototype

This technique is used to add public methods.

Container.prototype.stamp = function (string) {
    return this.member + string;
}

Private

Private members are made by the constructor. Ordinary vars and parameters of the constructor become the private members.

function Container(param) {
    this.member = param;
    var secret = 3;
    var that = this;
}

Privileged

A privileged method is able to access private methods, variables and is itself accessible to the public method and the outside.  Privileged methods are assigned with “this” within the constructor.

function Container(param) {
    this.member = param;

    this.service = function () {
        return this.member;
    };
}

References:

• http://javascript.crockford.com/private.html
• http://phrogz.net/JS/classes/OOPinJS.html
• https://developer.mozilla.org/en-US/docs/JavaScript/Guide/Inheritance_and_the_prototype_chain
• https://developer.mozilla.org/en-US/docs/JavaScript/Introduction_to_Object-Oriented_JavaScript

Function declaration

function name([param[, param[, ... param]]]) {
   statements
}

Example

function sum(a, b)
{
    return a + b;
}

name - The function name

param - The name of the argument to be passed to the function. A function can have up to 255 arguments.

statements - The body of the function

Function expression

function [name]([param] [, param] [..., param]) {
   statements
}

Example

var sum = function(a, b) { return a + b; }

Anonymous function

The name can be omitted in which case it becomes anonymous function. Anonymous functions can help make code more concise when declaring a function that will only be used in one place.

Example

var ar = [1,2,3];
var newAr = ar.map(function(e) { return e * 2});
console.log(newAr); //[2,4,6]

Function constructor

Function objects can be created with new operator

new Function (arg1, arg2, ... argN, functionBody)

Example

var sum = new Function('a','b', 'return a + b;');

arg1, arg2, … argN - zero or more names to be used by the function as argument names

functionBody - A string containing JavaScript statements forming the function body.

References

• Functions
• Why do you need to invoke an anonymous function on the same line?

Object

Object is an instance of a class.  All objects have a state and behavior.

Class

Class is the blueprint from which individual objects are created

Inheritance

Object-oriented programming allows classes to inherit commonly used state and behavior from other classes. In Java programming language, each class is allowed to have one direct superclass, and each superclass has the potential for an unlimited number of subclasses.

Interface

Methods form the object’s interface with the outside world. An interface is a group of related methods with empty bodies.  Interface separates implementation and defines the structure. It is useful when the implementation changes frequently.  Interface forms a contract between the class and the outside world.

Abstract Class

Abstract classes cannot be instantiated.  It can only be used as a super class for other classes that extend the abstract class.  Abstract classes are declared with keyword abstract.  Abstract class methods can have implementations. Abstract class’s methods can’t have implementation only when declared abstract.

Encapsulation

Encapsulation is inclusion within a program object of all the resources needed for the object to function.  It allows class to change its internal implementation without hurting the overall functioning of the system.

Polymorphism

Polymorphism is the ability to request that the same operations be performed by a wide range of different types of things.

Method overloading

Ability to define several methods all with the same name

Method overridding

Subclass overrides a specific implementation of a method that is already provided by one of its super classes.

References

• http://docs.oracle.com/javase/tutorial/java/concepts/object.html
• http://www.codeproject.com/Articles/22769/Introduction-to-Object-Oriented-Programming-Concep#OOP