Extending Classes In A Modular JavaScript Application Architecture Using RequireJS

friend.js

// Define the Friend model class. This extends the core Model.
define(
	[
		"./model"
	],
	function( Model ){


		// I return an initialized object.
		function Friend( name ){

			// Call the super constructor.
			Model.call( this );

			// Store the name.
			this._name = name;

			// Return this object reference.
			return( this );

		}


		// The Friend class extends the base Model class.
		Friend.prototype = Object.create( Model.prototype );


		// Define the class methods.
		Friend.prototype.getName = function(){

			return( this._name );

		};


		// -------------------------------------------------- //
		// -------------------------------------------------- //


		// Return the base Friend constructor.
		return( Friend );


	}
);

main.js

// Load the application.
require(
	[
		"./model/friend"
	],
	function( Friend ){


		// Create a few instances of Friend so that we can see
		// how inherited functionality has been propogated.
		var friends = [
			new Friend( "Sarah" ),
			new Friend( "Tricia" ),
			new Friend( "Joanna" )
		];

		// Now, iterate over each friend to output the name (which
		// is part of the FRIEND class) and the ID (which is part of
		// the inhereted MODEL class).
		for (var i = 0 ; i < friends.length ; i++){

			console.log(
				friends[ i ].getName(),
				":",
				friends[ i ].getInstanceID()
			);

		}


	}
);

model.js

// Define the base / core Model class.
define(
	function(){


		// I am the internal, static counter for the number of models
		// that have been created in the system. This is used to
		// power the unique identifier of each instance.
		var instanceCount = 0;


		// I get the next instance ID.
		var getNewInstanceID = function(){

			// Precrement the instance count in order to generate the
			// next value instance ID.
			return( ++instanceCount );

		};


		// -------------------------------------------------- //
		// -------------------------------------------------- //


		// I return an initialized object.
		function Model(){

			// Store the private instance id.
			this._instanceID = getNewInstanceID();

			// Return this object reference.
			return( this );

		}


		// I return the current instance count. I am a static method
		// on the Model class.
		Model.getInstanceCount = function(){

			return( instanceCount );

		};


		// Define the class methods.
		Model.prototype = {

			// I return the instance ID for this instance.
			getInstanceID: function(){

				return( this._instanceID );

			}

		};


		// -------------------------------------------------- //
		// -------------------------------------------------- //


		// Return the base Model constructor.
		return( Model );


	}
);