Electron Event Dispatcher

Helps you to organize communication between BrowserWindows, main/renderer IPCs, Sockets or any other EventEmitters in your Electron applications.

Installation

NPM:

$ npm install electron-event-dispatcher

Yarn:

$ yarn add electron-event-dispatcher

Usage

lib/device-events-dispatcher.js

const EventDispatcher = require('electron-event-dispatcher');
 
class DeviceEventsDispatcher extends EventDispatcher {
  constructor(driver, ipcMain) {
    super();
    
    // driver event handlers
    this.connect(driver, {
      connected: () => {
        // send `device-connected` event to all bound windows
        this.broadcast('device-connected');
      },
      disconnected: () => {
        // send `device-disconnected` event to all bound windows
        this.broadcast('device-disconnected');
      },
      data: (data) => {
        // send device data to all bound windows
        this.broadcast('device-data-received', data);
      }
    });
    
    // windows' (renderer) event handlers
    this.connect(ipcMain, {
      'get-device-state': (event) => {
        // respond to the requesting browser window
        event.sender.send('device-state', {
          connected: driver.connected || false
        });
      }
    });
  }
  
  /**
   * Override start/stop if you want to add some pre/post hooks.
   * @return {Promise} 
   */
  start() {
    // add some pre-start logic...
    
    return super.start()
      .then(() => {
        // add some post-start logic...
      });
  }
  
  /**
   * Override start/stop if you want to add some pre/post hooks.
   * @return {Promise} 
   */
  stop() {
    // add some pre-stop logic...
    
    return super.stop()
        .then(() => {
          // add some post-stop logic...
        });
    }
}
 
module.exports = DeviceEventsDispatcher;

app/main.js

const {app, BrowserWindow, ipcMain} = require('electron');
const DeviceEventsDispatcher = require('../lib/device-events-dispatcher');
const DeviceDriver = require('../lib/device-driver'); // an example event emitter
 
let mainWindow;
let settingsWindow;
let deviceEventsDispatcher;
 
function createMainWindow() {
  mainWindow = new BrowserWindow({ ... });
  mainWindow.loadUrl('../main.html');
  
  deviceEventsDispatcher.attach(mainWindow);
  
  mainWindow.on('closed', () => {
    mainWindow = null;
  });
}
 
function createSettingsWindow() {
  settingsWindow = new BrowserWindow({ ... });
  settingsWindow.loadUrl('../settings.html');
    
  deviceEventsDispatcher.attach(settingsWindow);
    
  settingsWindow.on('closed', () => {
    settingsWindow = null;
  });
}
 
app.on('ready', () => {
  const driver = new DeviceDriver();
  deviceEventsDispatcher = new DeviceEventsDispatcher(driver, ipcMain);
  
  deviceEventsDispatcher.start()
    .then(() => createMainWindow());
});
 
app.on('window-all-closed', () => {
  deviceEventsDispatcher.stop()
    .then(() => {
      if (process.platform !== 'darwin') {
        app.quit();
      }
    });
});
 
app.on('activate', () => {
  deviceEventsDispatcher.start()
    .then(() => createMainWindow());
});

API

Class: EventDispatcher

An instance of EventDispatcher is a unit that represents an event hub between electron's BrowserWindows and any EventEmitters (electron's ipc, tcp/web sockets, device drivers, etc.).

#attach(window)

Attach a BrowserWindow instance to the event dispatcher. Attached windows will receive all #broadcast()ing events.

Param	Type	Description
window	BrowserWindow	Electron's BrowserWindow instance.

#detach(window)

Detach a given window from the event dispatcher.

Technically, removes a given window reference from the attached windows collection to give'em be garbage collected.

Note that windows are detached automatically on closed.

Param	Type	Description
window	BrowserWindow	Electron's BrowserWindow instance.

#broadcast(event, [...args])

Broadcast an event to all attached windows.

Param	Type	Description
event	String	The name of the event to broadcast.
[...args]	EventEmitter	Any number of event-related arguments.

#connect(emitter, handlers)

Connect event emitter handlers in the context of this dispatcher.

Param	Type	Description
emitter	EventEmitter	An event emitter instance.
handlers	Object<String, Function>	An event => function object map, where event is a name of event to handle and function is a handler of this event.

#disconnect(emitter)

Disconnect event emitter handlers from this dispatcher.

Param	Type	Description
emitter	EventEmitter	An event emitter instance.

#start() ⇒ Promise

Start the event dispatcher. Binds all #connect()ed event emitters' handlers.

#stop() ⇒ Promise

Stop the event dispatcher. Unbinds all #connect()ed event emitters' handlers.

#restart() ⇒ Promise

Restart the event dispatcher.

#isRunning ⇒ boolean

Returns true if the event dispatcher is running.

Contributing

Feel free to dive in! Open an issue or submit PRs.

Running tests

In your terminal run:

$ npm test

or

$ yarn test

License

Licensed under MIT © 2017 Holy Krab Labs