import { of, Observable } from 'rxjs'; import { flatMap } from 'rxjs/operators';

function getData(): Observable { return of(1, 2, 3); }

function processData(value: number): Observable { return of(Processed: ${value}); }

getData() .pipe( flatMap(data => processData(data)) ) .subscribe(result => { console.log(result); // Output: Processed: 1 });

In the above example, we first define a function called `getData` which returns an Observable containing the numbers 1, 2, and 3. Then, we define a function called `processData` which converts each value in the Observable to a new Observable containing the processed string.

After calling the `getData` function, we use the `pipe` operator to apply the `flatMap` operator. The `flatMap` operator converts the Observable returned by the `getData` function to the new Observable returned by the `processData` function and flattens it. Finally, we output the processed result in the subscribe method.

By using the `flatMap` operator, we can conveniently return a value from the subscribe method. This approach is useful when dealing with asynchronous operations, as we can return a value without blocking the main thread and use it elsewhere.