SamplePlugin.js

/*
 * An example of
 * 1. Using the YUI 3 module system to encapsulate a custom class for reuse
 * 2. Creating a Plugin class
 * 3. Using Y.Base.create to generate the class
 */

// YUI.add(
//     "dash-separated-module-name",
//     function (Y) { Y.MyModule = ...; },
//     version_string,
//     module_metadata);
// NOTE YUI.add is a *static* method on the YUI global

// Create a module named sample-plugin
YUI.add('sample-plugin', function(Y) {

    // Signature of Y.Base.create(..) is
    // Y.Base.create(
    //     name_string,                  e.g. "camelCase"
    //     ClassToExtend,                e.g. Y.Base or Y.Widget
    //     array_of_extension_Classes,   e.g. [Y.WidgetStdMod]
    //     obj_of_prototype_members_and_methods,   (see below)
    //     static_members_and_methods);            (see below)
    // @returns a class constructor function

    // Create Y.Plugin.SamplePlugin class from Y.Base with no extensions
    Y.namespace('Plugin').SamplePlugin = Y.Base.create("sample", Y.Base, [], {

        // Prototype properties and methods

        // (Prefer attributes over properties for) Public instance properties
        foo: "default value for instance.foo property (public)",

        // Underscore prefix (quasi) private properties for common internal refs
        _type : null,
        
        initializer : function(config) {
            // Code that runs at instantiation (constructor code) goes here
        },
        
        somePublicMethod: function () {
            var val = this.get('myAttribute');

            this.set('myAttribute', "new value");

            // etc
        },

        _quasiPrivateMethod: function () {
            // publicly available, but implementers shouldn't access directly
        }

    }, {

        // Static members and methods

        // Namespace applied to the plugged instance to house the plugin API.
        // e.g. host.plug(Y.Plugin.SamplePlugin);  host.sample.somePublicMethod()
        NS : "sample",

        // Instance attributes made available via instance.get('attributeName')
        // instance.set('attributeName', "new value");
        ATTRS : {
            attributeName : {
                value : "default value",
                validator: Y.Lang.isString
                // see also setter, getter, writeOnce, readOnly, etc
            },
            
            anotherAttribute : {
                value : null,
                setter : function(val) {
                    if (val === true) {
                        return "a new value to assign to the attribute";
                    } else if (val % 2) {
                        // don't update attribute value
                        return Y.Attribute.INVALID_VALUE;
                    }
                    
                    return val; // is stored as the new value
                }
            }
        }
    });
}, 'v0.0.1' , { requires : [ 'plugin' ] });


(elsewhere)
YUI().use('sample-plugin', function (Y) {
    ...
    instance.plug(Y.Plugin.SamplePlugin, { someAttribute: "this value" });

});