server.js

// server.js
// where your node app starts

// init project
const express = require("express");
const path = require("path");
const app = express();

// Load environment variables from the `.env` file.
require("dotenv").config();

// we've started you off with Express,
// but feel free to use whatever libs or frameworks you'd like through `package.json`.

// This facilitates the correct frontend routing - DO NOT TOUCH
const port = process.env.PORT;
if (port == 3000) {
  // http://expressjs.com/en/starter/static-files.html
  app.use(express.static(path.join(__dirname, `../frontend/vanilla`)));
  app.use(
    "/images",
    express.static(path.join(__dirname, `../frontend/reactjs/src/images`))
  );

  // http://expressjs.com/en/starter/basic-routing.html
  app.get("/", function(request, response) {
    response.sendFile(path.join(__dirname, `../frontend/vanilla/index.html`));
  });

  serverStartLog = [
    `🚀  Server running locally: http://localhost:3000/`,
    `Backend API served from "backend/server.js"`,
    `Frontend served from "frontend/vanilla"`
  ];
} else {
  serverStartLog = [
    `Backend API served from "backend/server.js"`,
    `Frontend served from "frontend/reactjs"`
  ];
}

// Implement your API routes here
app.get("/config", (req, res) => {
  res.json({
    stripePublishableKey: process.env.STRIPE_PUBLISHABLE_KEY
  });
});

// listen for requests :)
const server = app.listen(port, function() {
  console.log(...serverStartLog);
});