gistfile1.js

// Creates a new App and View instance.
var app  = new Y.App(),
    view = new Y.View();

// Overrides the view's `render()` method to render text into its `container`.
view.render = function () {
    this.get('container').set('text', 'Hello World!');
    return this;
};

// Renders the app and view, then sets the view as the app's `activeView`.
app.render().showView(view.render());