snabbdom-jsx

Write Snabbdom views with Babel's JSX.

Features:

• Transform Babel JSX templates to Snabbdom virtual nodes
• Straightforward mapping from JSX attributes to Snabbdom data attributes using namespaces
• JSX Components are simples functions (attributes, children) => vnode. No more messy classes.

Usage

/** @jsx html */

import { html } from '../../snabbdom-jsx';

const patch = snabbdom.init([...]);

const mydiv = <div>Hello JSX</div>

patch(document.getElementById('placeholder'), vnode);

The /** @jsx html */ pragma at the top tells Babel to use the html function instead of the React.createElement default. The html function takes arguments passed from Babel and generate virtual nodes as expected by Snabbdom's patch function.

Mapping JSX attributes

A quick remainder: In snabbdom, most of the functionalities like toggling classes, styles and setting properties on DOM elements are delegated to separate modules.

For example

const myInput = h('input', { 
  props: { type: 'text' }       // handled by the props module
  on: { change: someCallback }, // handled by the eventlisteners module
  class: { class1: isEnabled }  // handled by the class module
  ...
})

Each module handles a portion of the data attributes (the object in the parameter to h). And each portion is stored inside a namespace, for example, event attributes are placed inside the on namespace, class attributes inside the class namespace and so on.

By default all attributes listed in the JSX element are placed inside the props namespace.

<input type="text" />

Is equivalent to

h('input', { props: { type: 'text' } })

To attach event listeners, we use the on- prefix

<button on-click={ callback } />

// is equivalent to

h('button', { on: { click: callback } })

This a generic rule: to map a JSX attribute to a specific module, you need to prefix the attribute with pref- where pref is the namespace used by the module in Snabbdom. As in the example above, all attributes with the on- prefix will be placed inside the the on namespace.

Another example using the class namespace

<div
  class-visible={isVisible}
  class-enabled={isEnabled}>
  
  ...
</div>

// is equivalent to

h('div', { 
  class: { visible: isVisible, enabled: isEnabled } 
}, [...])

But you can also specifies an unique object the same way as in the h function, this is useful when you have a dynamic object

<div
  style={ ({fontWeight: 'bold', color: 'red'}) }>
  
  ...
</div>

// is equivalent to

h('div', { 
  style: {fontWeight: 'bold', color: 'red'} 
}, [...])

You can mix both styles, the result will be a merge of all attributes

<div
  class={ ({visible: isVisible}) }
  class-enabled={isEnabled}>
  
  ...
</div>

JSX Components

In React/JSX you can create components and use them inside other components

var HelloMessage = React.createClass({
  render: function() {
    return <div>Hello {this.props.name}</div>;
  }
});

React.render(<HelloMessage name="John" />, mountNode);

Instead of classes, Snabbdom-jsx components are simple functions of type (attributes, children) => vnode.

//HelloMessage : (attrs, body) -> vnode
const HelloMessage = ({name}) =>
  <div on-click={ _ => alert('Hi ' + name) }>
    {name}
  </div>;


var vnode = <HelloMessage name="Yassine" />

If you're wondering how Components would fit in a large application, you can look into the todomvc example. The application is implemented using the Elm architecture. For more information see React-less Virtual DOM with Snabbdom : functions everywhere!