lin3s-event-bus
v0.10.0
Published
Simple but powerful event bus written in ES2015
Downloads
12
Readme
EventBusJS
Simple but powerful event bus written in ES2015
Installation
The recommended and the most suitable way to install is through Yarn:
$ yarn add lin3s-event-bus
or alternatively through NPM:
$ npm install --save lin3s-event-bus
Basic Usage
// your-dom-js-file.js
import {onDomReady, onDomLoaded, onWindowResized} from 'lin3s-event-bus';
const onReady = (domReadyEvent) => {
console.log('DOM is ready!');
};
const onLoaded = (domLoadedEvent) => {
console.log('window is loaded!');
};
const onResized = (windowResizedEvent) => {
const
newWindowHeight = windowResizedEvent.windowWidth,
newWindowWidth = windowResizedEvent.windowWidth;
console.log('window is resized!', newWindowWidth, newWindowHeight);
};
onDomReady(onReady);
onDomLoaded(onLoaded);
onWindowResized(onResized);
onNodeAdded
This helper method will subscribe to the NodeAddedObserver for DOM injection lookups. Each time a
css selector
-matching DOM node is added to the document's body, your passed callback wil be called. In other words,
you will be notified if a DOM node is injected into the document's body and your provided css selector
matches that
DOM node.
This is really helpful for defining a component's behaviour independently of the time of the component being added to the page. For example, if we want to trigger some logic, or initialize a component after being injected to the DOM dinamically.
For instance:
// your-dom-js-file.js
import {onDomReady, onNodeAdded} from 'lin3s-event-bus';
import MyComponent from './MyComponent';
const LOOKUP_CSS_SELECTOR = '.js-my-component';
const initMyComponent = (domNode) => {
const myComponent = new MyComponent(domNode);
// Whatever...
};
const onReady = () => {
const myComponents = document.querySelectorAll(LOOKUP_CSS_SELECTOR);
myComponents.forEach(myComponent => initMyComponent(myComponent));
// `rootNode` is the `document` by default.
onNodeAdded({selector: LOOKUP_CSS_SELECTOR, rootNode: document}, nodeAddedEvent => {
nodeAddedEvent.nodes.forEach(myComponentNode => initMyComponent(myComponentNode));
});
};
onDomReady(onReady);
Unsubscribing a subscriber
In the following example we are showing how to unsubscribe a previously subscribed subscriber. Every shortcut method returns the associated subscriber, so we can unsubscribe it later on via the LifeTimeEventPublisher or the OneTimeEventPublisher.
// your-dom-js-file.js
import {onWindowResized, LifeTimeEventPublisher} from 'lin3s-event-bus';
const onResized = (windowResizedEvent) => {
const
newWindowHeight = windowResizedEvent.windowWidth,
newWindowWidth = windowResizedEvent.windowWidth;
console.log('window is resized!', newWindowWidth, newWindowHeight);
};
const windowResizedSubscriber = onWindowResized(onResized);
// later on
LifeTimeEventPublisher.unsubscribe(windowResizedSubscriber);
Usage with priorities
In the following example there are two modules that are listening the WindowResizedEvent
event, but the module-b.js
is listening the event with higher priority than the module-a.js
so, the module-b.js
's onResized subscriber
always is executed before the module-a.js
's subscriber.
// module-a.js
import {onWindowResized} from 'lin3s-event-bus';
const onResized = (windowResizedEvent) => {
// This will be called after module-a.js onResized callback
const
newWindowHeight = windowResizedEvent.windowWidth,
newWindowWidth = windowResizedEvent.windowWidth;
console.log('Module A - window is resized!', newWindowWidth, newWindowHeight);
};
onWindowResized(onResized, 0);
// module-b.js
import {onWindowResized} from 'lin3s-event-bus';
const onResized = (windowResizedEvent) => {
// This will be called before module-b.js onResized callback
const
newWindowHeight = windowResizedEvent.windowWidth,
newWindowWidth = windowResizedEvent.windowWidth;
console.log('Module B - window is resized!', newWindowWidth, newWindowHeight);
};
onWindowResized(onResized, 1);
Extending the EventBus - Custom Events
In order to extend the Core.Event
and publish/subscribe to them, you must firstly implement your custom Event:
// CustomEvent module
import {Core} from 'lin3s-event-bus';
class CustomEvent extends Core.Event {
static NAME = 'YOUR_CUSTOM_EVENT';
constructor(payloadObject) {
super(CustomEvent.NAME);
this.payloadObject = payloadObject;
}
}
export default CustomEvent;
After implementing CustomEvent
class, you should code the custom EventSubscriber
. Using the previously defined
CustomEvent
custom event:
// CustomEventSubscriber module
import {Core} from 'lin3s-event-bus';
import CustomEvent from './CustomEvent';
class CustomEventSubscriber extends Core.EventSubscriber {
constructor(aCallback, aPriority) {
super(aCallback, aPriority);
}
isSubscribedTo(anEvent) {
// You can define your own custom validation logic. But at least, the event's name must match.
return anEvent.getName() === event.getName();
}
}
export default CustomEventSubscriber;
Finally, you should publish the CustomEvent
and subscribe to the CustomEvent
. If your event will be published
more than once you should publish it through the LifeTimeEventPublisher
instance. Otherwise, if you need to publish
the event just once (for example, a ComponentHasBeenInitializedEvent
), you should publish it through
the OneTimeEventPublisher
instance.
Publishing:
// Publishing the CustomEvent
import {Core} from 'lin3s-event-bus';
// or
import {LifeTimeEventPublisher} from 'lin3s-event-bus';
import {OneTimeEventPublisher} from 'lin3s-event-bus';
import CustomEvent from './CustomEvent';
const payload = {
// ...
};
const customEvent = new CustomEvent(payload);
Core.LifeTimeEventPublisher.publish(customEvent);
Core.OneTimeEventPublisher.publish(customEvent);
// or
LifeTimeEventPublisher.publish(customEvent);
OneTimeEventPublisher.publish(customEvent);
Subscribing:
// Subscribing to the CustomEvent
import {Core} from 'lin3s-event-bus';
// or
import {LifeTimeEventPublisher} from 'lin3s-event-bus';
import {OneTimeEventPublisher} from 'lin3s-event-bus';
import CustomEventSubscriber from './CustomEventSubscriber';
const customEventSubscriber = new CustomEventSubscriber((customEventInstance) => {
const payloadObject = customEventInstance.payloadObject;
// Whatever...
});
Core.LifeTimeEventPublisher.subscribe(customEventSubscriber);
Core.OneTimeEventPublisher.subscribe(customEventSubscriber);
// or
LifeTimeEventPublisher.subscribe(customEventSubscriber);
OneTimeEventPublisher.subscribe(customEventSubscriber);