Ractive.js vs Marko Widgets

Ractive fully supports a templating language. To be more precise, views are written with a variant of Mustache, which is also extended to support inline JavaScript expressions. Soon it will be able to support other templating languages.

Ractive has a concept of proxy events, which translate a user action (e.g. a mouseclick) defined via an event directive into an intention (e.g. 'select this option'). This allows you to handle user interaction in a readable, declarative fashion.
on-click='activate'
with arguments:
on-click = 'activate: {{a}}, {{b}}'
It's activate (and not click, nor your function name) that is the name of the handler event that will be fired for any registered handlers created via
ractive.on('activate', your_handler)
ractive.on('activate', your_another_handler)

Of course, Ractive also supports method calls like on-click='toggle(foo)'

Two-way binding can be turned off by those that are concerned it may be a source of bugs.

They have a great interactive tutorial which makes the learning process easy peasy. You will get into it within a couple of minutes.

Instead of relying on the DOM, Ractive implements a virtual DOM from scratch, allowing it to calculate precisely what needs to be patched during the next screen refresh. This is orders of magnitude faster than fiddling with the DOM itself.

Using Marko and Marko Widgets to render UI components on the server was shown to be 10x faster than React. A benchmark application was built using both Marko+Marko Widgets and React and the results of rendering a page of 100 search results on the server was measured and compared. Both the Marko Widgets code and the React code used a very similar UI components-based appraoch.

Marko Widgets supports stateful UI components. Marko Widgets will automatically rerender a UI component if its internal state changes. A UI component's state is stored in the this.state property that is a vanilla JavaScript object. All changes to the state should go through the this.setState(name, value) method (or this.replaceState(newState))

Marko Widgets utilizes the morphdom module for updating the DOM and that module was shown to be very competitive with React and virtual-dom.

Marko Widgets does not rely on a virtual DOM abstraction. Instead, the real DOM is always the source of truth. When updating the DOM, the newly rendered DOM is compared with the real DOM.

Marko Widgets updates the DOM using a DOM diffing/patching algorithm to minimize the number of changes to the DOM when rerendering a UI component due to state changes. The DOM diffing/patching is handled by the independent morphdom library.

The following code illustrates how the render(input) method exported by a UI component's JavaScript module can be used to render a UI component and insert the resulting HTML into the DOM:

require('./app-hello')
    .render({
        name: 'John'
    })
    .appendTo(document.body)

Updates to the DOM are deferred until all state changes have completed for the current tick. That is, changing a widget's state will not cause the UI component's DOM to immediately be updated.

Marko Widgets offers a simple mechanism for declaratively binding DOM event and custom event listeners to widget handler methods. For example:

<button type="button" w-onClick="handleClick">
    Click Me
</button>

And then in the JavaScript:

module.exports = require('marko-widgets').defineComponent({
    // ...
    handleClick: function(event, el) {
        this.doSomething();
    }
});

Marko is a fast and lightweight, general purpose HTML-based templating engine that compiles templates to CommonJS modules and supports streaming, async rendering and custom tags. Marko is used for rendering UI components and Marko Widgets is used to bind client-side behavior to rendered UI components. Marko can be used independently of Marko Widgets and this makes it suitable in all situations where HTML rendering is needed.

When utilizing server-side rendering of a UI, Marko Widgets does not require that the UI be rerendered again in the browser just to bind behavior. Instead, extra information is passed down from the server to the client to allow Marko Widgets to efficiently bind widgets to UI components rendered on the server.

The runtime for Marko Widgets is extremely small. The runtime is very small and this makes Marko Widgets much simpler and easier to understand and debug. Marko Widgets offloads much of the work and complexity to compile time code so that the work required at runtime is minimal.

Marko Widgets supports the concept of "scoped" IDs. With scoped IDs, a nested DOM element or nested widget can be given an ID that is unique within the scope of the containing widget. At runtime the actual ID will be the scoped ID prefixed with the ID of the parent widget. A reference nested widget can be obtained using the this.getWidget(scopedId) method and a reference to a nested DOM element can be obtained using the this.getEl(scopedId) method.

For example:

<div class="my-app" w-bind>
    <button type="button" w-onClick="handleButtonClick">
        Click Me
    </button>

    <alert-overlay visible="false" w-id="alert">
        This is a test alert.
    </alert-overlay>

    <div w-id="clickMessage" style="display: none;">
        You clicked the button!
    </div>
</div>

And then in the JavaScript code:

module.exports = require('marko-widgets').defineComponent({

    // ...

    handleButtonClick: function(event, el) {
        var alertWidget = this.getWidget('alert');

        // Call the `show()` function implemented by the alert widget:
        alertWidget.show();

        var clickMessageEl = this.getEl('clickMessage');
        clickMessageEl.style.display = 'block';
    }
});

Marko Widgets supports efficient event delegation to avoid attaching DOM event listeners to each DOM node. Instead, Marko Widgets attaches event listeners on the document.body event for events that bubble. Events captured at the root are efficiently delegated out to widgets.

The following code illustrates how a UI component can be embedded in a Marko template:

<div>
    <app-hello name="Frank"/>
</div>