@lifaon/rx-js-light/src/observer-observable-pair/build-in/source/built-in/unicast-source/create-unicast-source.mjs

Blazing fast Observables

import {freeze} from "../../../../../misc/helpers/freeze.mjs";
export function createUnicastSource() {
  let _emitFunction = null;
  const emit = value => {
    if (_emitFunction !== null) {
      _emitFunction(value);
    }
  };
  const subscribe = emit => {
    if (_emitFunction === null) {
      let running = true;
      _emitFunction = emit;
      return () => {
        if (running) {
          running = false;
          _emitFunction = null;
        }
      };
    } else {
      throw new Error(`Max one observer allowed`);
    }
  };
  return freeze({
    getObserver: () => {
      return _emitFunction;
    },
    emit,
    subscribe
  });
}