@applicaster/zapp-react-dom-app/Polyfills/DeviceEventEmitter/index.js

Zapp App Component for Applicaster's Quick Brick React Native App

const _DeviceEventEmitter = {};

export const DeviceEventEmitter = (function () {
  let listeners = {};

  function getListeners(eventName) {
    if (!eventName) {
      return listeners;
    }

    return listeners[eventName] || [];
  }

  function addListener(eventName, listener) {
    const currentListeners = getListeners(eventName);
    listeners[eventName] = [listener, ...currentListeners];

    return {
      remove() {
        const listenersForEvent = getListeners(eventName);

        listeners[eventName] = listenersForEvent.filter(
          (_listener) => _listener !== listener
        );
      },
    };
  }

  function removeListener(eventName, listener) {
    const listenersForEvent = getListeners(eventName);

    listeners[eventName] = listenersForEvent.filter(
      (_listener) => _listener !== listener
    );
  }

  function emitEvent(eventName, payload) {
    const eventListeners = getListeners(eventName);

    eventListeners.forEach((eventListener) => {
      eventListener(payload);
    });
  }

  const deviceEventEmitterInstance = {
    addListener,
    removeListener,
    emitEvent,
  };

  if (process.env.NODE_ENV === "test") {
    deviceEventEmitterInstance.getListeners = getListeners;

    deviceEventEmitterInstance.reset = function () {
      listeners = {};
    };
  }

  return deviceEventEmitterInstance;
})(_DeviceEventEmitter);