Pipe RxJS observable to existing subject

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observable
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GitLab launches Collective on Stack Overflow ,There is existing subject that is in use:, Meta Stack Overflow ,And there is another observable (another subject in this example):

Since Subject is already an observer with methods next(), error() and complete() you can just subscribe it to any Observable:

const fooSubject = new BehaviorSubject(null);

const barSubject = new Subject();
barSubject.subscribe(fooSubject);

barSubject.next('bar');
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#4379 Was swept under the rug. Let's fix this, it is a pain for people using RxJS. For example you cannot build your Angular app for production unless you type the the variable as any, it can really throw people off., Projects , Projects 2 ,Of course pipe returns a new Observable, however a Subject is just a specialized type of Observable

const subject$ = new Subject().pipe() // :: Observable
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💡 If you want the last emitted value(s) on subscription, but do not need to supply a seed value, check out ReplaySubject instead!,​BehaviorSubject - In Depth Dev Reference,​BehaviorSubject​📰 - Official docs,📁 Source Code: https://github.com/ReactiveX/rxjs/blob/master/src/internal/BehaviorSubject.ts​

// RxJS v6+import { BehaviorSubject } from 'rxjs';​const subject = new BehaviorSubject(123);​// two new subscribers will get initial value => output: 123, 123subject.subscribe(console.log);subject.subscribe(console.log);​// two subscribers will get new value => output: 456, 456subject.next(456);​// new subscriber will get latest value (456) => output: 456subject.subscribe(console.log);​// all three subscribers will get new value => output: 789, 789, 789subject.next(789);​// output: 123, 123, 456, 456, 456, 789, 789, 789
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Using Observable with AsyncPipe,An Observable is an entity that emits (or publishes) multiple data values (stream of data) over time and asynchronously.,In this tutorial, you have learned what an Observable is — An object that emits or publishes values over time and asynchronously.,You learned about cold and hot Observables — hot refers to when the Obseravble starts publishing values when it’s created even before getting any subscriptions.

let ob$ = Observable.create((observer) => {
   observer.next("A new value!");
});
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To use observable we need it to import from the rxjs library. If you are intend to use the pipe standalone function, then you also need to import it as well. All the operators are available in the library rxjs/operators.,Here is the example of using pipe with map & filter operator.,The following table lists some of the commonly used operators,We can also use the pipe as a standalone function to compose operators and re use the pipe at other places.

The pipe method of the Angular Observable is used to chain multiple operators together. We can use the pipe as a standalone method, which helps us to reuse it at multiple places or as an instance method. In this tutorial, we will take a look at the pipe and learn how to use it in an Angular Application. We will show you examples of pipe using map, filter & tap operators.

pipe

The pipe method of the Angular Observable is used to chain multiple operators together. We can use the pipe as a standalone method, which helps us to reuse it at multiple places or as an instance method. In this tutorial, we will take a look at the pipe and learn how to use it in an Angular Application. We will show you examples of pipe using map, filter & tap operators.

pipe

The pipe method of the Angular Observable is used to chain multiple operators together. We can use the pipe as a standalone method, which helps us to reuse it at multiple places or as an instance method. In this tutorial, we will take a look at the pipe and learn how to use it in an Angular Application. We will show you examples of pipe using map, filter & tap operators.

pipe

The pipe method of the Angular Observable is used to chain multiple operators together. We can use the pipe as a standalone method, which helps us to reuse it at multiple places or as an instance method. In this tutorial, we will take a look at the pipe and learn how to use it in an Angular Application. We will show you examples of pipe using map, filter & tap operators.

map

The pipe method of the Angular Observable is used to chain multiple operators together. We can use the pipe as a standalone method, which helps us to reuse it at multiple places or as an instance method. In this tutorial, we will take a look at the pipe and learn how to use it in an Angular Application. We will show you examples of pipe using map, filter & tap operators.

filter

The pipe method of the Angular Observable is used to chain multiple operators together. We can use the pipe as a standalone method, which helps us to reuse it at multiple places or as an instance method. In this tutorial, we will take a look at the pipe and learn how to use it in an Angular Application. We will show you examples of pipe using map, filter & tap operators.

tap
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The projection function will receive 'World' as its input parameter x, and will create the string Hello World!. map wraps the project function in an observable, which then emits the string value Hello World!. Remember, operators always return observables.,In this example, the observable returned by of('World’) is the source observable, and the single value 'World' is going to be pipe'd through to map’s projection function, which looks like this:,We’ve seen that operators like map and filter are functions which take in and return observables.,It cleans up Observable.prototype by removing operators

In this example, the observable returned by of('World’) is the source observable, and the single value 'World' is going to be pipe'd through to map’s projection function, which looks like this:

< > Copyx => `Hello ${x}!` // projection function
   // It's used like this:
   of ('World').pipe(map(x => `Hello ${x}!`));
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