Setting up flask - webpack environment in docker

I have been working on a flask app using 3 docker containers (postgres, nginx and one for the flask app itself). As for the front end, I am currently using jquery.

I am now going to work on making my web app progressive - service works and all!

My research is pointing me towards using webpack (and replacing jquery with react), however my attempts at getting webpack added to my docker setup are failing miserably and I've just become progressively more confused by the myriad of new web frameworks I've read about over the past few evenings.

Could someone kindly explain conceptually how webpack will alter my current docker environment, if at all? (docker-compose below)

I also tried the other approach of creating an entirely separate webpack-react project outside of any docker container. But I'm stuck thinking how I would use webpack's watch mode from within a docker container?

Any further suggested reading material or handy guides on the matter would be much appreciated and thanks for putting up with my rudimentary questions.

version: '3'
services:
  db:
    image: "postgres:9.6.5"
    volumes:
      - "dbdata:/var/lib/postgresql/data"
    env_file:
      - env_file
    networks:
      - db_nw
    flaskapp:
    build: .
    env_file:
      - env_file
    volumes:
      - .:/opt/services/flaskapp/src
    networks:
      - db_nw
      - web_nw
    depends_on:
      - db
  nginx:
    image: "nginx:1.13.5"
    ports:
      - "8080:80"
    volumes:
      - ./conf.d:/etc/nginx/conf.d
    networks:
      - web_nw
    depends_on: 
      - flaskapp
networks:
  db_nw:
    driver: bridge
  web_nw:
    driver: bridge
volumes:
  dbdata: