how to use the fromeventpattern function from the rxjs library in typescript

The fromEventPattern function in the rxjs library creates an Observable from an event pattern. This function takes two arguments:

1. addHandler: a function that takes a handler function and attaches it to an event source
2. removeHandler: a function that takes the handler function and detaches it from the event source

Here is an example of how to use the fromEventPattern function in TypeScript:

index.ts
import { fromEventPattern } from 'rxjs';

// Define the addHandler function
const addClickListener = (listener: (event: MouseEvent) => void) => {
  document.addEventListener('click', listener);
};

// Define the removeHandler function
const removeClickListener = (listener: (event: MouseEvent) => void) => {
  document.removeEventListener('click', listener);
};

// Create an observable from the event pattern
const clicks$ = fromEventPattern(
  addClickListener, // addHandler function
  removeClickListener // removeHandler function
);

// Subscribe to the Observable
clicks$.subscribe(event => console.log(event));
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In this example, we create an Observable clicks$ that emits each time the user clicks on the document. We use the fromEventPattern function to create the Observable, passing in the addClickListener and removeClickListener functions. Finally, we subscribe to the clicks$ Observable to log the MouseEvent to the console each time a click occurs.