How to run node/yarn in docker-compose?

Question

Docker

My docker-compose.yml

version: "3.8"
services:
  yarn:
    image: node:14-alpine
    container_name: jtt-yarn
    restart: unless-stopped
    command: sh -c "yarn install && yarn run prod"
    ports:
      - 3000:3000
    working_dir: /var/www/
    volumes:
      - ./:/var/www/
    networks:
      - jtt

  db:
    image: mysql:5.7
    container_name: jtt-db
    restart: unless-stopped
    environment:
      MYSQL_DATABASE: ${DB_DATABASE}
      MYSQL_ROOT_PASSWORD: ${DB_PASSWORD}
      MYSQL_PASSWORD: ${DB_PASSWORD}
      MYSQL_USER: ${DB_USERNAME}
      SERVICE_TAGS: dev
      SERVICE_NAME: mysql
    volumes:
      - ./docker-compose/mysql:/docker-entrypoint-initdb.d
    networks:
      - jtt

  nginx:
    image: nginx:alpine
    container_name: jtt-nginx
    restart: unless-stopped
    ports:
      - ${DOCKER_NGINX_PORT}:80
    volumes:
      - ./:/var/www
      - ./docker-compose/nginx:/etc/nginx/conf.d/
    networks:
      - jtt

networks:
  jtt:
    driver: bridge

But such code

docker-compose exec app node --version

does not work in a container.
how to run a script in a container

node app.js