RxJS 观察者和订阅者是一回事吗？

Question

RxJS introduces Observables, a new Push system for JavaScript. An Observable is a Producer of multiple values, "pushing" them to Observers (Consumers).

Subscribing to an Observable is analogous to calling a Function.

要调用 Observable，我们应该从 Observable 对象本身调用 subscribe() 函数，并将观察者作为由 observable 传递的数据的消费者传递，例如：

observable.subscribe( { /*this is an observer*/ } );

还有这个 documentation 说：

What is an Observer? An Observer is a consumer of values delivered by an Observable. Observers are simply a set of callbacks, one for each type of notification delivered by the Observable: next, error, and complete. The following is an example of a typical Observer object:

另一方面，第一份文件说：

The Observable constructor takes one argument: the subscribe function. The following example creates an Observable to emit the string 'hi' every second to a subscriber.

import { Observable } from 'rxjs';

const observable = new Observable(function subscribe(subscriber) {
  const id = setInterval(() => {
    subscriber.next('hi')
  }, 1000);
});

When calling observable.subscribe with an Observer, the function subscribe in new Observable(function subscribe(subscriber) {...}) is run for that given subscriber. Each call to observable.subscribe triggers its own independent setup for that given subscriber.

所以实体 Subscriber 只是在创建一个新的 Observable 时传递给订阅函数的参数？如果不是，订阅者是谁？

观察者和订阅者是同一个实体吗？如本文所述documentation

为什么调用 observable.subscribe({observer as call backs}) 的代码不是可观察对象的订阅者？就像函数的 return 值的消费者是进行函数调用的代码。

COMPLETE DESIGN PATTERN EXPLANATION

Answer 1

观察者

const observer = {
  next: v => /* code for next callback*/,
  error: err => /* code for error callback*/,
  complete: () => /* code for completion callback*/
}

可观察

const observable1 = from([1,2,3,4,5]);
const observable2 = of(1,2,3,4,5);
const observable3 = new Observable(observer => {
  observer.next(1);
  observer.next(2);
  observer.next(3);
  observer.next(4);
  observer.next(5);
  observable.complete();

  return { // return a subscription
    unsubscribe: () => /* code for unsubscribe callback */
  };
});

订阅并使用返回的订阅

// Store a subscription 
const subscription = observable3.subscribe(observer);
// Invoke the unsubscribe callback defined by the observable.
subscription.unsubscribe();

好的。那什么是订户？

[Subscriber] Implements the Observer interface and extends the Subscription class. While the Observer is the public API for consuming the values of an Observable, all Observers get converted to a Subscriber... Subscriber is a common type in RxJS, and crucial for implementing operators, but it is rarely used as a public API.

观察者和订阅者是一回事吗？有点，是吗？取决于你问的具体程度。

考虑一下：

observable3.subscribe({
  next: v => /* code for next callback */
});

obsevable3.subscribe(
  v => /* code for next callback */
);

第一个是只定义了一个观察者属性的对象。第二个只是一个 lambda 函数。他们最终都产生了基本相同的订阅者。

RxJS 观察者和订阅者是一回事吗？

RxJS Is Observer and Subscriber the same thing?

observable

rxjs

观察者

订阅

可观察

订阅并使用返回的订阅

好的。那什么是订户？