Express中的JSON.stringify api响应

Question

I'm reading some codes and I saw this

router.post('/', (req, res) => {
  const {author, message} = req.body;

  if (author === undefined) {
    res.status(400);
    res.setHeader('Content-Type', 'application/json');
    res.send(JSON.stringify({ message: 'Every message requires an author' }));
    return
  }

  res.redirect('/');

});

I've no clue why it need to use JSON.stringify, can't I just do res.send({ message: 'Every message requires an author' }) ?

And the route has an unit test, it used JSON.parse

describe('when the author is blank', () => {
      it('renders an error message', async () => {
        const message = 'Server Testing';

        const response = await request(app)
          .post('/messages')
          .send({message});

        assert.equal(response.status, 400);
        assert.equal(JSON.parse(response.text).message, 'Every message requires an author')
        });
    });

I don't see the point of using JSON.stringify and JSON.parse, please enlighten me.

Answer 1

You can remove but it may lead to some unexpected results at times even if you are passing exact json. I will share an example with you. I was working on a project where in I need to send a hotel id in json format .I was sending the exact format but server was not accepting that and was throwing 500 error so it's always better to stay on a safer side and declare your data in a separate variable and pass in that data using json.stringify format in the get/post request.It comes good practices. So it's always good to have those :-)

Answer 2

Server side use:

res.json({a: 123})

instead of

res.send(JSON.stringify({a: 123}))

http://expressjs.com/en/api.html#req.body

Then in the unit test:

const response = await request(app).post('/messages').send({message});

const data = await response.json();