Namespace

A namespace is a container which allows developers to bundle up all functionality under a unique, application-specific name. In JavaScript a namespace is just another object containing methods, properties and objects.

It is very important to note that there is no language-level difference between regular object and namespaces as there is in some other object-oriented languages.

The idea behind creating a namespace in JavaScript is simple: one global object is created and all variables, methods and functions become properties of that object. Use of namespaces also minimizes the possibility of name conflicts in an application.

Let's create a global object called MYAPP:

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

Here in above code sample we have first checked whether MYAPP is already defined (either in same file or in another file). If yes, then use the existing MYAPP global object, otherwise create an empty object called MYAPP which will encapsulate method, functions, variables and objects.

We can also create sub-namespaces:

// sub namespace
MYAPP.event = {};

Below is code syntax for creating namespace and adding variable, function and method:

// Create container called MYAPP.commonMethod for common method and properties
MYAPP.commonMethod = {
  regExForName: "", // define regex for name validation
  regExForPhone: "", // define regex for phone no validation
  validateName: function(name){
    // Do something with name, you can access regExForName variable
    // using "this.regExForName"
  },
 
  validatePhoneNo: function(phoneNo){
    // do something with phone number
  }
}

// Object together with the method declarations
MYAPP.event = {
    addListener: function(el, type, fn) {
    //  code stuff
    },
   removeListener: function(el, type, fn) {
    // code stuff
   },
   getEvent: function(e) {
   // code stuff
   }
  
   // Can add another method and properties
}

// Syntax for Using addListener method:
MYAPP.event.addListener("yourel", "type", callback);