p5.js-web-editor/server/controllers/user.controller.js

import User from '../models/user'
import passport from 'passport'
import path from 'path'

export function createUser(req, res, next) {
	const user = new User({
		username: req.body.username,
    email: req.body.email,
    password: req.body.password
  });

  User.findOne({email: req.body.email}, (err, existingUser) => {
		if (existingUser) {
			return res.status(422).send({ error: 'Email is in use' });
		}
		user.save((err) => {
			if (err) { return next(err); }
			req.logIn(user, (err) => {
				if (err) {
					return next(err);
				}
				res.json({
					email: req.user.email,
					username: req.user.username
				});
			});
		});
  });

}