JS: jQuery Plugin Pattern

jquery.plugin.js

/*
 * 'Highly configurable' mutable plugin boilerplate
 * Author: @markdalgleish
 * Further changes, comments: @addyosmani
 * Licensed under the MIT license
 */

// Note that with this pattern, as per Alex Sexton's, the plugin logic
// hasn't been nested in a jQuery plugin. Instead, we just use
// jQuery for its instantiation.

;(function( $, window, document, undefined ){

	// our plugin constructor
	var Plugin = function( elem, options ){
		this.elem = elem;
		this.$elem = $(elem);
		this.options = options;

		// This next line takes advantage of HTML5 data attributes
		// to support customization of the plugin on a per-element
		// basis. For example,
		// <div class=item' data-plugin-options='{"message":"Goodbye World!"}'></div>
		this.metadata = this.$elem.data( 'plugin-options' );
	};

	// the plugin prototype
	Plugin.prototype = {
		defaults: {
			message: 'Hello world!'
		},

		init: function() {
			// Introduce defaults that can be extended either
			// globally or using an object literal.
			this.config = $.extend({}, this.defaults, this.options,
			this.metadata);

			// Sample usage:
			// Set the message per instance:
			// $('#elem').plugin({ message: 'Goodbye World!'});
			// or
			// var p = new Plugin(document.getElementById('elem'),
			// { message: 'Goodbye World!'}).init()
			// or, set the global default message:
			// Plugin.defaults.message = 'Goodbye World!'

			this.sampleMethod();
			return this;
		},

		sampleMethod: function() {
			// eg. show the currently configured message
			// console.log(this.config.message);
		}
	}

	Plugin.defaults = Plugin.prototype.defaults;

	$.fn[pluginName] = function ( options ) {
		return this.each(function () {
			if (!$.data(this, 'plugin_' + pluginName)) {
				$.data(this, 'plugin_' + pluginName, new Plugin( this, options ));
			}
		});
	};

	//optional: window.Plugin = Plugin;

})( jQuery, window , document );