JavaScript

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Singleton objects in JavaScript

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what the f**k is apply, call and bind?

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use of ‘use strict’?

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this & prototype functions

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Objects in JavaScript

As we all know,objects are instance of a class.

2 ways to create an object in JavaScript It's important to note that there are no classes(except in ES6) in JavaScript. Functions can be used to somewhat simulate classes, but in general JavaScript is a class-less language. Everything is an object. And when it comes to inheritance, objects inherit from objects, not classes from classes as in the classical languages.

Using Functions

Using Object literals

Using Functions The most common way to create an object.First of we define a function to create an object of the class ( function ) by using new keyword. If you want to add a behavior to your object, you can go for constructor and add methods to the object during construction or give your class a prototype. If you don't have behavior associated with an object (i.e. if the object is just a container for data/state), I would use an object literal.

function myClass(foo,bar) {         this.foo = foo;         this.bar = bar;

        this.verify = function () {                 return this.foo === this.bar;         }; }

// or: myClass.prototype.verify = function () {         return this.foo === this.bar; }; //creating object var newInstance = new  myClass(42,43); // calling member function newInstance. verify();

Using Object literals If you don't need anything beyond a simple container of data, go with a simple literal.No behaviour associated with the object, we can go for object literals.The object created using Object literals are Singleton.

var data = {         foo: 42,         bar: 43 };

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Classes in JavaScript

Defines the object's characteristics. A class is a template definition of an object's properties and methods.

JavaScript is a prototype-based language and contains no class statement, such as is found in C++ or Java (Classes are introduced in ES6).

In JavaScript , functions are classes.

function myClass() {        var privateVariable;        var privateMethod = function(){                 /* function definition*/        }

       function anotherPrivateMethod(){                 /* function definition*/         }

       this.publicVariable;        this.publicFunction = function(){                 /* function definition*/        } }

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Namespace in JavaScript

A container which lets developers bundle all functionality under a unique, application-specific name. Creating a namespace in JavaScript is simple, create one global object, and all variables, methods, and functions become properties of that object.

Use of namespaces also reduces the chance of name conflicts in an application,since each application's objects are properties of an application-defined global object.

// global namespace var MYAPP = MYAPP || {};

//creating Sub namespace MYAPP.event = {};

Naming namespace,you'll capitalize the first letter. If your app requires use of global scope, it's good practice to use a namespace like this to prevent name conflicts (just as jQuery uses $ as a namespace in order to access all the methods and properties of its API).

var myApplication = {         getInfo:function(){                 /* function definition   */         },         models : {

        },         views : {                 pages : {}         },         collections : {         } };

For get to know more about Namespace patterns click here

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JavaScript is Object Oriented?

Object-oriented to the core, JavaScript features powerful, flexible capabilities

Terminologies

Namespace

Class

Object

Property

Method

Constructor

Inheritance

Encapsulation

Abstraction

Polymorphism

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So what is dynamic typed?

Whether or not a language is dynamic typically refers to the type of binding the compiler does: static or late binding.

Static binding simply means that the method is bound at compile time.

Dynamic languages are the opposite. They do their work at runtime. They do little or no checking for the existence of methods at compile time but instead do it all at runtime.

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What is JavaScript ?

JavaScript is an object-oriented dynamic language with types and operators, standard built-in objects, and methods.

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Remember, before you can be great, you’ve got to be good. Before you can be good,you’ve got to be bad. But before you can even be bad, you’ve got to try.

Art Williams