redux-doctitle/src/middleware.js

import {TITLE_ACTIONS_SET} from "./defs";

export const documentTitleMiddlewareFactory = (defaultTitleParts = []) => {
  return (store, getState) => next => action => {
    if (action.type == TITLE_ACTIONS_SET) {
      let titleParts = [].concat(defaultTitleParts);
      if (action.title) {
        titleParts.unshift(action.title);
      }

      window.document.title = titleParts.join(" | ");
    } else {
      next(action);
    }
  };
};