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

To use the lastValueFrom function from the rxjs library in JavaScript, first, you need to import it from the library like this:

index.tsx
import { lastValueFrom } from 'rxjs';
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Then, you can use the lastValueFrom function with an observable that you want to get the last value emitted from it. Here is an example:

index.tsx
import { interval } from 'rxjs';
import { lastValueFrom } from 'rxjs';

const observable = interval(1000); // emits a value every 1 second
(async () => {
  const lastValue = await lastValueFrom(observable);
  console.log(`The last value emitted is ${lastValue}`);
})();
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In the example above, we created an observable that emits a value every 1 second using the interval function from rxjs, then we used the lastValueFrom function to get the last value emitted from the observable.

Note that the lastValueFrom function returns a promise, so we need to use async and await to handle the result.

In this example, the output will be similar to this:

index.tsx
The last value emitted is 4
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because interval emits values starting from 0, and after 5 seconds (which is the time needed to emit 5 values), the last value emitted will be 4.