elm-ssr.js

const fs = require('fs')
const path = require('path')
const { promisify } = require('util')
const express = require('express')
const elmStaticHtml = require('elm-static-html-lib').default

const readFile = promisify(fs.readFile)
const app = express();

const pathToClient = path.resolve(__dirname, '../client/src')

app.use(async (req, res) => {

  const model = { url: req.url }
  const options = { model, decoder: 'Main.decode' }

  const [ indexHtml, appHtml ] = await Promise.all([
    readFile(path.resolve(__dirname, '../client/static/index.html')),
    elmStaticHtml(pathToClient, "Main.view", options)
  ])

  res.send(indexHtml.toString().replace('{{app}}', appHtml))
})


app.listen(4000, () => console.log('http://localhost:4000'))