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

The buffer function in the RxJS library allows you to collect emitted values from a stream until a specified closingNotifier Observable emits a value.

Here is an example of how to use the buffer function to collect every 3 clicks from a button element:

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

const button = document.querySelector('button');

const click$ = fromEvent(button, 'click');

const bufferedClick$ = click$.pipe(
  buffer(click$.pipe(
    // emits a value after 3 seconds
    // to close buffer and emit collected clicks
    delay(3000)
  ))
);

bufferedClick$.subscribe(bufferedClicks => {
  console.log(bufferedClicks);
  // output: [MouseEvent, MouseEvent, MouseEvent]
});
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In this example, we use the fromEvent function to create an Observable of mouse click events on a button element. We then use the buffer operator to collect every three emitted events from the click$ stream until the closingNotifier Observable (created by the delay function) emits a value to close the buffer and emit the collected clicks as an array.

Finally, we subscribe to the bufferedClick$ stream and log the array of collected click events to the console.