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

The switchMapTo operator in RxJS is used to map each source value to the same inner Observable, and flatten the result to a single Observable emitting the flattened result.

Here's an example of how to use switchMapTo in JavaScript:

index.tsx
import { of, interval } from 'rxjs';
import { switchMapTo } from 'rxjs/operators';

const source$ = of('A', 'B', 'C');

// Define an inner Observable that will emit a value every second
const inner$ = interval(1000);

source$.pipe(
  // Map each source value to the same inner Observable
  switchMapTo(inner$)
).subscribe(val => console.log(val));

// Output:
// 0
// 1
// 2
// 3
// ...
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In this example, we created an Observable source$ that emits three values ('A', 'B', 'C'). We then defined an inner Observable inner$ that emits a value every second using the interval function.

We then used the switchMapTo operator to map each value emitted by source$ to the same inner$ Observable. The result is a flattened Observable that emits the values from the inner$ Observable (0, 1, 2, 3, ...) as they are produced, regardless of the source value.

The final subscribe call logs the output to the console.