server.js

const path = require('path')
const express = require('express')
const fs = require('fs')
const {renderToString} = require('@vue/server-renderer')
const manifest = require('./dist/server/ssr-manifest.json')

const server = express()

const appPath = path.join(__dirname, './dist', 'server', manifest['app.js'])
const createApp = require(appPath).default

server.use('/img', express.static(path.join(__dirname, './dist/client', 'img')))
server.use('/js', express.static(path.join(__dirname, './dist/client', 'js')))
server.use('/css', express.static(path.join(__dirname, './dist/client', 'css')))
server.use(
    '/favicon.ico',
    express.static(path.join(__dirname, './dist/client', 'favicon.ico'))
)

server.get('*', async (req, res) => {
    const createAppResult = createApp();
    const { app, router } =  createAppResult;

    await router.push(req.url)
    await router.isReady()

    const appContent = await renderToString(app)

    fs.readFile(path.join(__dirname, '/dist/client/index.html'), (err, html) => {
        if (err) {
            throw err
        }

        html = html
            .toString()
            .replace('<div id="app">', `<div id="app">${appContent}`)
        res.setHeader('Content-Type', 'text/html')
        res.send(html)
    })
})

const port = process.env.VUE_SSR_PORT || 8181

console.log(`You can navigate to http://localhost:${port}`)

server.listen(port)