added mediator pattern

Author: AnjanishKumar

pattern/mediator-pattern.js

@@ -0,0 +1,58 @@
+var window = window || null;
+var Mediator = ( function( window, undefined ) {
+
+	function Mediator() {
+		this._topics = {};
+	}
+
+	Mediator.prototype.subscribe = function mediatorSubscribe( topic, callback ) {
+		if( ! this._topics.hasOwnProperty( topic ) ) {
+			this._topics[ topic ] = [];
+		}
+
+		this._topics[ topic ].push( callback );
+		return true;
+	};
+
+	Mediator.prototype.unsubscribe = function mediatorUnsubscrive( topic, callback ) {
+		if( ! this._topics.hasOwnProperty( topic ) ) {
+			return false;
+		}
+
+		for( var i = 0, len = this._topics[ topic ].length; i < len; i++ ) {
+			if( this._topics[ topic ][ i ] === callback ) {
+				this._topics[ topic ].splice( i, 1 );
+				return true;
+			}
+		}
+
+		return false;
+	};
+
+	Mediator.prototype.publish = function mediatorPublish() {
+		var args = Array.prototype.slice.call( arguments );
+		var topic = args.shift();
+
+		if( ! this._topics.hasOwnProperty( topic ) ) {
+			return false;
+		}
+
+		for( var i = 0, len = this._topics[ topic ].length; i < len; i++ ) {
+			this._topics[ topic ][ i ].apply( undefined, args );
+		}
+		return true;
+	};
+
+	return Mediator;
+
+} )( window );
+
+// example subscriber function
+var Subscriber = function ExampleSubscriber( myVariable ) {
+  console.log( myVariable );
+};
+
+// example usages
+var myMediator = new Mediator();
+myMediator.subscribe( 'some event', Subscriber );
+myMediator.publish( 'some event', 'foo bar' ); // console logs "foo bar"