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https://github.com/cristiammercado/ng-event-bus
RxJS-based message bus service for Angular.
https://github.com/cristiammercado/ng-event-bus
angular event event-bus message-bus rxjs
Last synced: 7 days ago
JSON representation
RxJS-based message bus service for Angular.
- Host: GitHub
- URL: https://github.com/cristiammercado/ng-event-bus
- Owner: cristiammercado
- License: mit
- Created: 2019-04-08T14:55:12.000Z (over 5 years ago)
- Default Branch: main
- Last Pushed: 2024-10-11T00:31:06.000Z (29 days ago)
- Last Synced: 2024-10-19T08:22:45.206Z (21 days ago)
- Topics: angular, event, event-bus, message-bus, rxjs
- Language: TypeScript
- Size: 1.77 MB
- Stars: 49
- Watchers: 1
- Forks: 9
- Open Issues: 10
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
- awesome-angular - ng-event-bus - RxJS-based message bus service for Angular. (Table of contents / Third Party Components)
- fucking-awesome-angular - ng-event-bus - RxJS-based message bus service for Angular. (Table of contents / Third Party Components)
README
# ng-event-bus
RxJS-based message/event bus service for Angular apps inspired by [NgRadio](https://github.com/govorov/ng-radio). Inject it in your application module. You can check [npm page](https://www.npmjs.com/package/ng-event-bus).
[](https://circleci.com/gh/cristiammercado/ng-event-bus)
[](https://badge.fury.io/js/ng-event-bus)
## Installation
`npm install --save ng-event-bus`
## Angular Compatibility Table
| Angular version | ng-event-bus version |
|-----------------|----------------------|
| 18.x | 7.x.x |
| 17.x | 6.x.x |
| 16.x | 5.1.x |
| 15.x | 5.0.x |
| 15.x | 5.0.x |
| 14.x | 4.x.x |
| 13.x | 4.x.x |
| 12.x | 3.x.x |
| 11.x | 2.x.x |
## Usage
First, import it:
`import { NgEventBus } from 'ng-event-bus';`
Then, inject it as a service (do not forget about providers) in your Angular application:
```
import { NgEventBus } from 'ng-event-bus';
@NgModule({
imports:[
...
],
providers: [
...,
NgEventBus,
...
],
```
`constructor(private eventBus: NgEventBus) { ... }`
Since you have `NgEventBus` instance in your app, you can use these methods for passing messages:
* `this.eventBus.cast(key, data)` - send a message to event bus.
* `this.eventBus.on(pattern)` - returns observable you can subscribe to listen events.
Where:
- `key` must be a string and must not be empty, otherwise it will throw an exception.
- `data` is optional and can be any type of object.
- `pattern` must be a string and must not be empty.
### Patterns
Patterns may contain multiple segments split by `:`. Use this feature to create namespaces for messages you cast. You can use `*` in `pattern` to subscribe to any matching segment, or use `**` to subscribe to all segments, starting from particular position.
For example, you can use `on('error:*')` and subscribe to all errors, including something like `error:http` or `error:internal` and so on:
```
this.eventBus.cast('app:start', 'started');
this.eventBus.cast('message:greet', 'Hi!');
this.eventBus.cast('message:bye', 'Bye!');
this.eventBus.on('app:start').subscribe((meta: MetaData) => {
console.log(meta.data); // will receive 'started' only
});
this.eventBus.on('message:greet').subscribe((meta: MetaData) => {
console.log(meta.data); // will receive 'Hi!'
});
this.eventBus.on('message:bye').subscribe((meta: MetaData) => {
console.log(meta.data); // will receive 'Bye!'
});
this.eventBus.on('message:*').subscribe((meta: MetaData) => {
console.log(meta.data); // will receive both 'Hi!' and 'Bye!'
});
this.eventBus.on('**').subscribe((meta: MetaData) => {
console.log(meta.data); // will receive all messages: 'started', 'Hi!' and 'Bye!'
});
```
### MetaData
When you subscribe to the observable, you can optionally get an instance of `MetaData` class. This instance contains information related to the emission of the event through the bus. The properties of this instance are:
- `id`: A unique identifier of the message sent through the events bus.
- `key`: Original key associated to the message.
- `data`: Data associated to message. It's optional.
- `timestamp`: Time in milliseconds in which the message was generated.
```
this.eventBus.cast('app:start', 'started');
this.eventBus.on('app:start').subscribe((meta: MetaData) => {
console.log(meta.id); // will print "d9c31eb0-b3f3-4764-a96d-6a703112a696"
console.log(meta.key); // will print "app:start"
console.log(meta.data); // will print "started"
console.log(meta.timestamp); // will print 1605934473553
});
```
```
this.eventBus.cast('message:bye', {message: 'bye'});
this.eventBus.on('**').subscribe((meta: MetaData) => {
console.log(meta.id); // will print "4945f28c-d2a5-4738-b7d1-f3df8f08422c"
console.log(meta.key); // will print "message:bye"
console.log(meta.data); // will print {message: 'bye'}
console.log(meta.timestamp); // will print 1605934709116
});
```
### Examples
These strings will match:
- `on('**' ).suscribe` can subscribe to any message with any segments count
- `on('a' ).suscribe` can subscribe to `cast('a', ...)`
- `on('a:b' ).suscribe` can subscribe to `cast('a:b', ...)`
- `on('a:b:c' ).suscribe` can subscribe to `cast('a:b:c', ...)`
- `on('a:**' ).suscribe` can subscribe to `cast('a:b:c', ...)`, `cast('a:b:c:d:e:f', ...)`
- `on('a:*:*' ).suscribe` can subscribe to `cast('a:b:c', ...)`, `cast('a:f:g', ...)`, `cast('a:n:m', ...)`
- `on('a:b:*' ).suscribe` can subscribe to `cast('a:b:c', ...)`, `cast('a:b:d', ...)`, but not `cast('a:b', ...)`
- `on('a:b:**').suscribe` can subscribe to `cast('a:b:c',. ..)`
- `on('*:b:*' ).suscribe` can subscribe to `cast('a:b:c', ...)`
- `on('a:*:*' ).suscribe` can subscribe to `cast('a:b:c', ...)`
### Need to unsubscribe (observable)?
Yes, in the normal scenario usage it's necessary you unsubscribe from the observable to avoid memory leaks. That happens because the library exposes an infinite observable. That's no exactly related to the library, but in the way in which the observables work in RxJS.
However, there are ways that you don't need to unsubscribe, for example if you use `.first()` in the pipe of the observable because using this method would turn it into a finite observable (It would apply in your case if you're just waiting for a one-time event).
I recommend you to read this [stackoverflow answer](https://stackoverflow.com/questions/50629357/rxjs-angular-unsubscribe-from-subjects/50633482#50633482) about a similar question.
## Release history & changelog
See the [Releases](https://github.com/cristiammercado/ng-event-bus/releases) page for a list of all releases, including changes.
## Help / Support
If you run into any issues, please email me at [[email protected]](mailto:[email protected]) or you can use the contact form in [my page](https://www.cristiammercado.com/en/#contact).
For bug reports, please [open an issue on GitHub](https://github.com/cristiammercado/ng-event-bus/issues/new).
## Contributing
1. [Fork it](https://github.com/cristiammercado/ng-event-bus).
2. Create your feature branch (`git checkout -b my-new-feature`).
3. Commit your changes (`git commit -am 'Added some feature'`).
4. Push to the branch (`git push origin my-new-feature`).
5. Create a new Pull Request.
## License
[MIT](https://github.com/cristiammercado/ng-event-bus/blob/master/LICENSE)