Javascript patterns

patterns.js

// namespace - single global variable for all news JS 
var news = news || {};

// Example of a singleton as a revealing module
// When you only need one of something
news.preferences = (function (app, global) {

    // Private variables
    var persistent = true;

    // Initialise Code
    
    // Functions      
    var isPersistent = function () {
        return persistent;
    };
            
    // Public interface
    return {
        isPersistent:	isPersistent
    };

}(news, this)); // <-- pass in app and global scope 

// Singleton usage (Why isn't this code inside some module, is it just dangling?)
news.preferences.isPersistent();


// Example of constructor function
// When you need multiple instances of something
news.Gallery = (function (app, global) {       

	// Constructor function
    var galleryConstructor = function Gallery(name, preferences) {
         this.name = name;
         this.shouldSaveChanges = preferences.isPersistent();
    };

	// Add instance functions to prototype
    galleryConstructor.prototype.show = function () {
        if (this.shouldSaveChanges) {
          // depending on prefs but without the global access
        }
    };
	
	// Return constructor function
    return galleryConstructor;
    
}(news, this));

// Constructor function usage
var myGallery = new news.Gallery('My gallery', news.preferences);