Hands-On Functional Programming with TypeScript

Creating observables from callbacks

It is also possible to create an observable that will iterate the arguments of a callback using the bindCallback function:

import { bindCallback } from "rxjs";import fetch from "node-fetch";function getJSON(url: string, cb: (response: unknown|null) => void) {    fetch(url)        .then(response => response.json())        .then(json => cb(json))        .catch(_ => cb(null));}const uri = "https://jsonplaceholder.typicode.com/todos/1";const observableFactory = bindCallback(getJSON);const observable = observableFactory(uri);const subscription = observable.subscribe(    (value) => console.log(value));subscription.unsubscribe();

The preceding example uses the node-fetch module because the fetch function is not available in Node.js. You ...