normalize-async.js

const normalizeChatAsync = ({ Messages, Users, ...rest }) => {
  let messagesIds = [];
  let usersIds = [];
  
  return new Promise((resolve) => {
    Promise.all(
      Messages.map(
        mes => Promise.resolve(mes)
                      .then(mes => mes.id)
      )
    ).then(mesIds => { 
      messagesIds = mesIds;
      if (usersIds.length > 0) {
        resolve({
          ...rest,
          Messages: messagesIds,
          Users: usersIds,
          enitities: {
            Messages,
             Users,
          },
        });
      }
    });
    Promise.all(
      Users.map(
        user => Promise.resolve(user)
                      .then(user => user.id)
      )
    ).then(uIds =>
      Object.keys( 
        uIds.reduce((acc, id) => {
          if (acc[id] == null) {
            acc[id] = true;
            return acc;
          }
          return acc;
        }, {})
      )
    ).then(uIds => {
      usersIds = uIds;
      
      if (messagesIds.length > 0) {
        resolve({
          ...rest,
          Messages: messagesIds,
          Users: usersIds,
          enitities: {
            Messages,
             Users,
          },
        });
      }
    });
  });
};