src/selectors/alerts.js

import { createSelector } from 'reselect';

/**
 * Селектор всех алертов
 */
export const alertsSelector = state => {
  return state.alerts || {};
};
/**
 * Селектор алертов по ключу(widgetId)
 */
export const makeAlertsByKeySelector = key =>
  createSelector(
    alertsSelector,
    alerts => alerts[key]
  );
/**
 * Селектор алерта по ключу(widgetId) и id алерта
 */
export const makeAlertByKeyAndIdSelector = (key, id) =>
  createSelector(
    makeAlertByKeyAndIdSelector(key),
    alerts => alerts[id]
  );