how to use the last function from the rxjs library in javascript

The last() operator in RxJS is used to retrieve the last value emitted by an observable. Here's an example of how to use it:

index.tsx
import { from } from 'rxjs';
import { last } from 'rxjs/operators';

const source = from([1, 2, 3, 4, 5]);
const example = source.pipe(last());

example.subscribe(value => console.log(value)); // Output: 5
206 chars
8 lines

In the above code, we first create an observable called source using the from() function. We then use the last() operator together with the pipe() method on this observable to create a new observable called example. Finally, we subscribe to example and log the last emitted value to the console.

Note that the last() operator will return an error if the source observable is empty, so be sure to handle this case appropriately.