如何在订阅完成之前等待函数执行？

Question

I want to subscribe to an Observable and then execute another function. My problem is, it takes a moment until the request is finished. However, the code just continues with its execution immediatly after the subscription has started.

I need some information that will be there after the Subscription is complete . Without that data, transformShopList() will fail. When I run the code, this is what happens.

How can you wait for the Subscription to finish, and then go on with the rest of the statements?

this.observable3.subscribe(
  ...
);
// wait here?
this.transformShopList();

Answer 1

You'll have this problem whatever you do in Javascript. Asynchronous tasks must be chained . Either with Promise , Observable or callback functions.

The right code is

this.observable3.subscribe((...) => {
  ...
  this.transformShopList();
});

Answer 2

An observable emits an event and your subscription receives it. Move your transform shop list inside the subscription response and it will execute when the observable emits.

https://angular.io/guide/observables