[](https://travis-ci.org/bougarfaoui/ng2-socket-io) [](https://badge.fury.io/js/ng-socket-io) [
],
providers: [],
bootstrap: [AppComponent]
})
export class AppModule { }
`
We need to configure `SocketIoModule` module using the object `config` of type `SocketIoConfig`, this object accepts two optional properties they are the same used here [io(url[, options])](https://github.com/socketio/socket.io-client/blob/master/docs/API.md#iourl-options).
Now we pass the configuration to the static method `forRoot` of `SocketIoModule`
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The `SocketIoModule` provides now a configured `Socket` service that can be injected anywhere inside the `AppModule`.
`typescript
import { Injectable } from '@angular/core';
import { Socket } from 'ng-socket-io';
@Injectable()
export class ChatService {
constructor(private socket: Socket) { }
sendMessage(msg: string){
this.socket.emit("message", msg);
}
getMessage() {
return this.socket
.fromEvent("message")
.map( data => data.msg );
}
}
`
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In this case we do not configure the `SocketIoModule` directly using `forRoot`. What we have to do is: extend the `Socket` service, and call `super()` with the `SocketIoConfig` object type (passing `url` & `options` if any).
`typescript
import { Injectable, NgModule } from '@angular/core';
import { Socket } from 'ng-socket-io';
@Injectable()
export class SocketOne extends Socket {
constructor() {
super({ url: 'http://url_one:portOne', options: {} });
}
}
@Injectable()
export class SocketTwo extends Socket {
constructor() {
super({ url: 'http://url_two:portTwo', options: {} });
}
}
@NgModule({
declarations: [
//components
],
imports: [
SocketIoModule,
//...
],
providers: [SocketOne, SocketTwo],
bootstrap: [/ AppComponent /]
})
export class AppModule { }
`
Now you can inject `SocketOne`, `SocketTwo` in any other services and / or components.
API
Most of the functionalities here you are already familiar with.
The only addition is the `fromEvent` method, which returns an `Observable` that you can subscribe to.
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Takes an event name and callback.
Works the same as in Socket.IO.
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Takes an event name and callback.
Works the same as in Socket.IO.
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Takes an event name.
Works the same as in Socket.IO.
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Sends a message to the server.
Optionally takes a callback.
Works the same as in Socket.IO.
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Takes an event name and returns an Observable that you can subscribe to.
You should keep a reference to the Observable subscription and unsubscribe when you're done with it.
This prevents memory leaks as the event listener attached will be removed (using `socket.removeListener`) ONLY and when/if you unsubscribe.
If you have multiple subscriptions to an Observable only the last unsubscription will remove the listener.
##### Example
You can also see this example with express.js.
`typescript
import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import { AppComponent } from './app.component';
import { SocketIoModule, SocketIoConfig, Socket} from 'ng-socket-io';
const config: SocketIoConfig = { url: 'http://localhost:8988', options: {} };
@Injectable()
class ChatService {
constructor(private socket: Socket) { }
sendMessage(msg: string){
this.socket.emit("message", msg);
}
getMessage() {
return this.socket
.fromEvent("message")
.map(data => data.msg );
}
close() {
this.socket.disconnect()
}
}
@NgModule({
declarations: [
AppComponent
],
imports: [
BrowserModule,
SocketIoModule.forRoot(config)
],
providers: [ChatService],
bootstrap: [AppComponent]
})
export class AppModule { }
``