在触发下一个事件之前，如何让一个可观察对象等待

Question

我在 Angular 项目中使用 RxJs。有两个科目

    s1.next()

    s1.subscribe(() => {
      // does some operation and then triggers s2 event
      s2.next()
    });

    s2.subscribe(() => {
      // does some operation and then ends.
    });

如何让 s1 等到 s2 完成它的工作。

Answer 1

在您的代码中，您需要显示那是什么类型的工作。我认为你不需要s2，你需要建立一个基于s1 emits的管道。

如果是请求 - 只需制作一个管道

s1.pipe(
  // s1 emits
  switchMap(() => {
    return this.http.get('url1');
  }),

  // one more request, once the first one has been finished.
  switchMap(() => {
    return this.http.get('url2');
  }),

).subscribe(response => {
  // 2 requests have been completed and we are here.
});

s1.next(); // triggers the flow.

在触发下一个事件之前，如何让一个可观察对象等待

How can I let an observable to wait before firing the next event

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