Handle POST requests

server.js

// Store the single image in memory.
let latestPhoto = null;

// Upload the latest photo for this session
app.post('/', (req, res) => {
  // Very light error handling
  if(!req.body) return res.sendStatus(400);

  console.log('got photo')

  // Update the image and respond happily
  latestPhoto = req.body.photo;
  res.sendStatus(200);
});