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

The switchScan function in the RxJS library combines the switchMap and scan operators to allow you to smoothly switch between streams and accumulate values over time. Here's how you can use it in JavaScript:

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

// Define a source stream with initial value
const source$ = of({ count: 0 });

// Define a function that returns a new stream based on a counter value
const createNewStream = (counterValue) => {
  return of({ count: counterValue + 1 });
};

// Use switchScan to switch to new streams based on accumulated values
const output$ = source$.pipe(
  switchScan((acc, curr) => createNewStream(acc.count), 0)
);

// Subscribe to the output stream to log the stream values
output$.subscribe((value) => console.log(value));
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In this example, switchScan takes two parameters – a function that returns a new stream based on the accumulated value and the current value, and an initial accumulator value of 0. The createNewStream function takes a counter value and returns a new stream that emits an object with the count property incremented by 1. The switchScan operator switches between the new streams returned by createNewStream as they are emitted, accumulating each new value along the way.

I hope that helps!