How to combine Vue app server and Express?

What you're looking for is the devServer option. If you're using vue cli 3, create a vue.config.js file in your main app directory, then add this block:

module.exports = {
  configureWebpack:{
  }, 
  devServer:{
    host: 'localhost',
    hot:true,
    port: 8080,  
    open: 'Chrome',
    proxy: { //https://cli.vuejs.org/guide/html-and-static-assets.html#disable-index-generation
      '/*':{ //everything from root
        target: 'http://localhost:3000',
        secure: false,
        ws: false,
      },
      '/ws/': { //web sockets
        target: 'http://localhost:3000',
        secure: false,
        ws: true
      },
      '!/':{ //except root, which is served by webpack's devserver, to faciliate instant updates
        target: 'http://localhost:3000/',
        secure: false,
        ws: false
      },
    }
  }
}

The port for your frontend can be on 8080 or whatever, and your backend on 7070, and you proxy your requests from your frontend node server on 8080 to your backend node server on 7070. This is for vue cli 3. For earlier versions you have to put the devServer option somewhere else IIRC, but I forget where. If you have problems with this, ask me and I can check it out.

Since Vue is only a frontend library, the easiest way to host it and do things like serve up assets is to create a simple Express friendly script that you can use to start a mini-web server. Read up quickly on Express if you haven’t already. After that, add express:

npm install express --save

Now add a server.js file to your project’s root directory :

// server.js
var express = require('express');
var path = require('path');
var serveStatic = require('serve-static');
app = express();
app.use(serveStatic(__dirname + "/dist"));
var port = process.env.PORT || 7070;
var hostname = '127.0.0.1';

app.listen(port, hostname, () => {
   console.log(`Server running at http://${hostname}:${port}/`);
 });

after that you could run :

 node server

and your project will be served at the given host and port

Assuming that you have already the dist directory, if you don't have it run :

npm run build

in order to generate it and you don't need to run npm run serve or npm run dev for ruuning Vue app