mongoose.js

db.once('open', function() {
  let UserSchema = mongoose.Schema({
    username: String,
    password: String
  })

  let User = mongoose.model('User', UserSchema)

  app.post('/signup', urlencodedParser, function(req, res) {
        username = req.body.username,
        password = req.body.password,
        salt = bcrypt.genSaltSync(10),
        hash = bcrypt.hashSync(password, salt)
        // Trying to assign a variable name to the constructor below
        new User({ username: username, password: hash })
  })
})