Hands-On Functional Programming with TypeScript

Creating observables from events

It is also possible to create an observable using an event as the source of the items in the stream. We can do this using the fromEvent function:

import { fromEvent } from "rxjs";const observable = fromEvent(document, "click");const subscription = observable.subscribe(    (value) => console.log(value));subscription.unsubscribe();

In this case, the item handler in the subscription will be invoked as many times as the click event takes place.

Please note that the preceding example can only be executed in a web browser. To execute the preceding code in a web browser, you will need to use a module bundler, such as Webpack. We will not cover this topic, since it is beyond the scope of this book.