//MODEL
var User = mongoose.model('User', { user: String, password: String, email: String });

//FUNCTION FOR CREATING A USER
function createUser(user, pass, email) {
    if(userExists(user)) return;
    var NewUser = new User({ user: user, password: pass, email: email });
    NewUser.save();
}

//FUNCTION FOR CHECKING IF A USER EXISTS
function userExists(user) {
  User.find({user: user}, function(err, docs) {
    if(!docs.length) {
      console.log('User does not exist: ' + user);
      return false;
    } else {
      console.log('User already exists: ' + user);
      return true;
    }
  })
}