server.js

const express = require('express');
const connectDB = require('./config/db');
const cors = require('cors');
const path = require('path');

const app = express();

// Connect Database
connectDB();

app.use(function(req, res, next) {
  res.header("Access-Control-Allow-Origin", '*');
  res.header("Access-Control-Allow-Credentials", true);
  res.header('Access-Control-Allow-Methods', 'GET,PUT,POST,DELETE,OPTIONS');
  res.header("Access-Control-Allow-Headers", 'Origin,X-Requested-With,Content-Type,Accept,content-type,application/json');
  next();
});

// Add Cors
app.use(cors({ origin: 'https://aqueous-river-48967.herokuapp.com' }));

// Init Middleware
app.use(express.json({ extended: false }));

// Define Routes
app.use('/api/auth', require('./routes/auth'));
app.use('/api/contacts', require('./routes/contacts'));
app.use('/api/users', require('./routes/users'));

// Serve static assets in production
if (process.env.NODE_ENV === 'production') {
  // Set static folder
  app.use(express.static('client/build'));

  app.get('*', (request, response) => response.sendFile(path.resolve(
    __dirname,
    'client',
    'build',
    'index.html'
  )));
};

const PORT = process.env.PORT || 8888;

app.listen(PORT, () => console.log(`Server started on port ${PORT}!`));