Flux-Reactions

A library to make easier the communication among React.js components using events.

Using events, a dispatcher is not needed anymore to create an app that follows a Flux architecture. Components emit DOM events and actions are listeners added to the document in order to react to those events, that's is why this library is called Reactions.

Since events are available in every browser, react.js components don't need to be attached to any library method to communicate with the rest of the page, that makes components 100% encapsulated and reusable.

Flux-Reactions is just an utility to reduce the boilerplate of dispatch custom events cross-browser, not a complete Flux implementation.

See A better Flux with DOM events to know the benefits of this approach.

Install

Flux-reactions comes in the shape of a UMD module to be used in Node.js and the browser. It is possible to install it using npm

npm install flux-reactions

Using bower

bower install flux-reactions

Or adding it directly to your page code for development flux-reactions.js(5KB), and minified flux-reactions.min.js(1KB).

Use

Flux-reactions comes with a mixin for React.js modules that allows to emit events easily using the trigger method. Let's create a counter component that emit an increment event whenever its button is clicked.

var Counter  = React.createClass({
    // Add the reaction mixin
    mixin: [Reactions.mixin],
    render: function(){
        return (
            <div className="counter">
                <span>{this.props.count}</span>
                <button onClick={ this.onIncrease }>Increase</button>
            </div>
        );
    },
    onIncrease: function(){
        // Emit an increase event with 1 as detail
        this.trigger('increase', 1);
    }
});

To create a reaction to the event, we can use the Reaction object as a hub.

Reactions.on( 'increase', function( e ){
    // Add the number passed as detail to the 
    // counter store ( 1 in this example)
    store.counter += e.detail;
});

The mixin also allow to listen to events emited by children components. Imagine a selectable list:

var List = React.createClass({
    mixin:[Reactions.mixin],
    // Events to listen are defined in the onEvents attribute
    onEvents: {
        // Add a listener to the selected event
        selected: function(e){
            // Select the item that emitted the event
            this.setState({selected: e.detail});
        }
    },
    getInitialState: function(){
        return {selected: -1};
    },
    render: function(){
        // Create a list of 3 items
        var items = [0,1,2].map( function( i ){
            return <Item text={ 'Item ' + i} index={ i } selected={ this.state.selected == i} />;
        });
        return <div>{ items }</div>;
    }
});
var Item = React.createClass({
    mixin:[Reactions.mixin],
    render: function(){
        return (
            // thenTrigger will emit a selected event on click
            <div onClick={ this.thenTrigger( 'selected', this.props.index ) }>
                { this.props.text }
            </div>
        );
    }
})

API

Reactions.on( eventName, callback )

Add a listener to some event, AKA creates a reaction. The reaction will receive the event as the only argument.

// Creates a reaction for the selected event
Reactions.on( 'selected', function( e ){
    console.log( 'Hey I am selected!');
});

Reactions.once( eventName, callback )

Add a listener to some events that will be called just once.

Reactions.off( eventName, callback )

Removes an event listener.

Reactions.trigger( eventName, detail )

Flux dispatcher uses the waitfor method to synchronize different actions. Using flux-reaction you can trigger a new event whenever a reaction has finished to coordinate several reactions for an event.

Reactions.mixin

A mixin to be used by react components. The mixin will add the following methods to the component:

trigger( eventName, detail )

Triggers the event in the DOM node of the component. The detail attribute of the event can be customized passing its value as the second argument.

thenTrigger( eventName, detail )

Returns a function than trigger the event with the given detail attribute. This is useful to trigger the event directly from the render method without creating a new function that does so.

var Item = React.createClass({
    mixin:[Reactions.mixin],
    render: function(){
        return (
            // thenTrigger will emit a selected event on click
            <div onClick={ this.thenTrigger( 'selected', this.props.index ) }>
                { this.props.text }
            </div>
        );
    }
})

listenTo( eventName, callback )

Listen to children events.

onEvents

Event listeners for children can also defined declaratively by using the component onEvents attribute. That attribute must be an object with the name of the events as keys and functions or name of methods of the current component as values:

onEvents: {
    selected: 'onSelected',
    removed: function(){
        console.log( 'removed' );
    }
}

A selected event on a children with trigger component's onSelected method. A removed event will trigger the function defined.

Those listeners will be added in this componentDidMount method.

Collaborate

This is a quick implementation of a crossbrowser event library to be used with React.js. There are some directions to work to:

• Add support for using EventEmitter make it work in the server.
• Study the alternatives to make it work with the future React Native.
• Add support for using it as a higher order component.

Any improvement that you may find is welcome.