jQuery Plugin

TSCreatePlugin.js

/*
	Make a jQuery plugin
	
	@param string name - Name of plugin
	@param string extend - Name of parent plugin to extend
	@param function onInit(element, instance) - a function that initialize the plugin instance on the element. To export methods, assign the functions to the instance.
	@param object defaults - a set of default values which can be accessed through instance.options
	
	Example:
	
	// Defining a plugin:	
	TSCreatePlugin($, 'hello', null, function onInit(elem, instance) {

		var privateVar = 'secret';
		function privateFunction() {}
		
		instance.foo = 'bar';
		instance.greet = function(name) { console.log(this.options.greetMessage + ', ' + name + '! I\'m a ' + elem.prop('tagName') + '.'); }
		instance.onDestroy = function() { delete this.foo; }
		
    }, {greetMessage:'Hello'});
	
	Usage:
	
	$(elem).hello({greetMessage:'Hola'});	// Initialize an instance associated with elem, may not be necessary for some plugins.
	$(elem).hello('greet', 'Guest');		// Invoke plugin methods
	$(elem).hello('foo');					// Get a property of the plugin instance
	$(elem).hello('destroy');				// Remove the plugin instance, calling instance.onDestroy if provided
	
	Note: It may not be a nice idea to invoke a plugin method without initializing the plugin instance previously because the arguments provided will be treated as initialization options.
	
*/
function TSCreatePlugin($, name, extend, onInit, defaults) {
	$.fn[name] = function(cmd, options) {
		var instanceKey = 'handy-plugin-'+name;
		var instance = this.data(instanceKey);
		var superInstance = null;

		if (cmd === undefined || typeof cmd == 'object') {
			options = cmd;
			cmd = null;
		}

		// special command: destroy
		if (cmd == 'destroy') {
			if (instance && typeof instance['onDestroy'] == 'function') {
				instance.onDestroy();
			}
			this.removeData(instanceKey);
			return this;
		}

		// special command: get the controller instance
		if (cmd == 'controller') {
			return instance;
		}

		// init instance
		if (!instance) {

			// super init
			if (extend && typeof this[extend] == 'function') {
				this[extend](cmd, options);
				superInstance = this[extend]('controller');
			}

			// create instance
			instance = $.extend({}, superInstance);
			this.data(instanceKey, instance);

			// merge options with default settings
			var optionsObject = typeof options == 'object'? options: null;
			instance.options = $.extend({}, defaults || {}, optionsObject || {});

			// init instance
			onInit(this, instance, superInstance);
		}

		// invoking methods / getting properties
		var args = []; for (var i = 1; i < arguments.length; i++) args.push(arguments[i]);
		if (typeof instance[cmd] == 'function') {
			var ret = instance[cmd].apply(instance, args);
			if (ret !== undefined) return ret;
		} else if (instance[cmd] !== undefined) {
			return instance[cmd];
		}
		return this;
	};
}