javascript - 如何在 rxjs 中做链式序列

Question

我想做这样的事:

this._myService.doSomething().subscribe(result => {
  doSomething()
});
.then( () => dosthelse() )
.then( () => dosanotherthing() )

所以我想像 promise 的那样链接 .then。我将如何在 Rxjs 中做到这一点？

this._myService.getLoginScreen().subscribe( result => {
      window.location.href = MyService.LOGIN_URL;
      /// I would like to wait for the site to load and alert something from       the url, when I do it here it alerts the old one
    });
   .then (alert(anotherService.partOfTheUrl())


getLoginScreen() {
  return this.http.get(myService.LOGIN_URL)
.flatMap(result => this.changeBrowserUrl())
.subscribe( result => //i want to do sth when the page is loaded//);
}

changeBrowserUrl(): Observable<any> {
return Observable.create( observer => {
window.location.href = myService.LOGIN_URL;
observer.next();
});
}

Answer 1

可观察对象的 then 等价于 flatMap。您可以在此处查看一些使用示例:

• RxJS Promise Composition (passing data)
• Why we need to use flatMap?
• RxJS sequence equvalent to promise.then()?

对于您的示例，您可以执行以下操作:

this._myService.doSomething()
  .flatMap(function(x){return functionReturningObservableOrPromise(x)})
  .flatMap(...ad infinitum)
  .subscribe(...final processing)

注意您的函数返回的类型，对于使用 flatMap 的链式 observable，您将需要返回一个 promise 或一个 observable。