如何在 Angular 2 中创建 RxJS 主题？

Question

I am able to create an Observable in my angular component in below mentioned way

...
...
import { Observable } from 'rxjs/Observable';
..
...
let observable = new Observable( function subscribe(observer) {
        observer.next(1);
        observer.next(2);
        observer.next(3);
        observer.next(4);
        setTimeout(() => {observer.next(5); },9000);
    });

But am not aware of how to create a Subject, can some one provide an example for the same?

Answer 1

Here's a plunker: http://plnkr.co/edit/jLtFLjWrvHGI0ZPHl10B?p=preview

import {Subject} from 'rxjs/Subject';

@Injectable()
export class MyService {

    public invokeEvent:Subject<any> = new Subject();

    constructor() {}
}

subscribe to it like an observable:

  constructor(private _myService: MyService) {
         this._myService.invokeEvent.subscribe((value) => {
           console.log(value); 
         });
       }

and push values to it like an observable again with next

  ngAfterViewInit(){
      this._myService.invokeEvent.next(1);
  }

Answer 2

Using Rx.Subject with Angular it is no different from using it without Angular , the main principle is the same, look at the example below

const subject = new Rx.Subject();
const subscription = subject.subscribe(
  (data) => console.log(data),
  (err) => console.log(err),
  () => console.log('Completed')
);

subject.next(1);
subject.next(2);
subject.next(3);
subject.complete();

<script src="https://unpkg.com/@reactivex/rxjs@5.0.0-beta.7/dist/global/Rx.umd.js"></script>

You need to make new instance Rx.Subject , then subscribe to it where you need to, and fire event.

Answer 3

You can do it by following code

 import { BehaviorSubject } from 'rxjs'; subject = new BehaviorSubject<string>(""); observer = this.subject.asObservable(); //TO FIRE NEXT EVENT this.subject.next("My next value"); // TO SUBSCRIBE EVENT this.observer.subscribe({ next: (value)=>{ console.log(value); // will return My next value } });