@lifaon/rx-js-light/src/observable/pipes/built-in/without-notifications/others/first/first-observable.mjs

Blazing fast Observables

import {asyncUnsubscribe} from "../../../../../../misc/helpers/async-unsubscribe.mjs";
export function firstObservable(subscribe) {
  return emit => {
    let running = true;
    const unsubscribe = subscribe(value => {
      if (running) {
        running = false;
        asyncUnsubscribe(() => unsubscribe);
        emit(value);
      }
    });
    return () => {
      if (running) {
        running = false;
        unsubscribe();
      }
    };
  };
}