sending value from server to client node js

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

via Simon Draymon