VERY IMPORTANT check if you have vue version 3

vue —version

npm uninstall if needed

check to make sure you have node 8.9 or higher node —version
update/upgrade if needed

optional, install and use yarn. https://yarnpkg.com/en/docs/install#mac-stable

vue create new_project - follow prompts, choose standard/recommended options cd new_project

touch server.js

npm install express or yarn add express

optional: vue add router vue add vuex

server.js

// Dependencies
const express = require('express')
const app = express()

// Port
// Allow use of Heroku's port or your own local port, depending on your environment
const PORT = process.env.PORT || 3000

// use public folder for static assets, like css
app.use(express.static('dist'))

app.use(express.urlencoded({extended:false}))
app.use(express.json())

// Listen
app.listen(PORT, ()=>{
  console.log('Listening on port: ', PORT  );
})

update package.json - careful to keep it as valid json!

add start and heroku-postbuild in scripts

heroku also recommends adding your version of node under engines

package.json

  "scripts": {
    "serve": "vue-cli-service serve",
    "build": "vue-cli-service build",
    "lint": "vue-cli-service lint",
    "start": "node server.js",
    "heroku-postbuild": "npm run build"
  },
  "engines": {
    "node": "10.11.0"
  },

start - tells heroku what to run in order to start the server

heroku-postbuild - runs the build scripts to compile your vue components

Note: you can now run your vue app with node server.js on localhost:3000 but it doesn’t have any of the dev features and it won’t be representative of what is on heroku. Also if you want to see changes you have to remember to run npm run build every time you want to see a change. So it’s better to just use yarn serve or npm run serve - just know that heroku is using it.

See the default app deployed with a couple of minor updates (done for the purpose to check that builds were working/updating)

https://warm-garden-59874.herokuapp.com/

yarn install

yarn run serve

yarn run build

yarn run test

yarn run lint

See Configuration Reference.