sending value from server to client node js

Question

I am registering a user and after successful registration I want alert something in client side. So, what I do in server side, after registration I'm sending a value "registered" then when it gets that value, my client side would know that user is registred but I don't know how to get that value in my client side.

router.post('/registration', function (req, res, next) {
    var stud = {
        username: req.body.username,
        email: req.body.email,
        password: req.body.password,
        admin: 0
    };

    mongo.connect(url, function (err, db) {
        assert.equal(null, err);
        db.collection('user-data').insertOne(stud, function (err, result) {
            assert.equal(null, err);
            console.log('Student inserted');
            db.close();
            res.json('registred');
        })
    })


});

My client side code

$('.MyForm').on('submit', function(event){
    event.preventDefault();


    $.ajax({
      url: '/registration',
      method: 'post',

      success: function(response){

      }
    })


  });   

There is not very much because I don't know what to do next

Answer 1

All you still need to do is put the alert in the callback to the ajax request

success: function(response) {
    alert('User registration succeeded!')
}

Answer 2

Since you're using HTTP protocol, why not use its cohesive response codes to indicate which action has happened? For example:

200 - user successfully created 400 - malformed input data 409 - one of unique user's model field has been already taken

And so on. Use method 'status' on response object to set appropriate return code. I assume that you are trying to create server with REST's rules in mind, therefore your endpoint should return freshly created entity on POST request.

mongo.connect(url, function (err, db) {
        assert.equal(null, err);
        db.collection('user-data').insertOne(stud, function (err, result) {
            if(err) {
              /* At this point, you may decide to check what error has been returned to decide which code will be returned*/
              return res.status(400).json(err);
            }
            console.log('Student inserted');
            db.close();
            res.status(200).json(result);
        })
    })

On client side, code might be much more pleasant to eye after you would refactor it to use jQuery's ( since ver. 1.5.1 )'Promise API'

$.ajax({
  url: 'http://localhost:8000',
  method: 'POST'
})
  .done(function( data ) {

  })
  .fail(function (reason) {

  })