如何将 Observable 转换为 ReplaySubject? [英] How to convert an Observable to a ReplaySubject?

问题描述

这是我现在正在做的将 Observable 转换为 ReplaySubject 的操作:

Here is what I'm doing now to convert an Observable to a ReplaySubject:

const subject = new Rx.ReplaySubject(1);

observable.subscribe(e => subject.next(e));

这是进行转换的最佳方式，还是有更惯用的方式?

Is this the best way to make the conversion, or is there a more idiomatic way?

推荐答案

如果你想传递所有 3 种类型的通知，你可以只使用 observable.subscribe(subject) 因为一个 Subject 已经表现得像观察者.例如:

You can use just observable.subscribe(subject) if you want to pass all 3 types of notifications because a Subject already behaves like an observer. For example:

let subject = new ReplaySubject();
subject.subscribe(
  val => console.log(val),
  undefined, 
  () => console.log('completed')
);

Observable
  .interval(500)
  .take(5)
  .subscribe(subject);

setTimeout(() => {
  subject.next('Hello');
}, 1000)

观看现场演示:https://jsbin.com/bayewo/2/edit?js，控制台

然而，这有一个重要的后果.由于您已经订阅了源 Observable，因此您将其从冷"变为热"(也许这在您的用例中无关紧要).

However this has one important consequence. Since you've already subscribed to the source Observable you turned it from "cold" to "hot" (maybe it doesn't matter in your use-case).

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