HTTP Servers & APIs — Series 3

Preview — 3 of 10 questions

What happens?

javascript

const server = http.createServer((req, res) => {
  res.write('partial');
  res.setHeader('X-Trace', 'abc');
  res.end('done');
});

AThe header is sent with the response, since headers are flushed at end().

BIt throws ERR_HTTP_HEADERS_SENT: the first write() flushes the status line and headers, so nothing can be added afterwards.

CThe header is silently ignored and the response completes normally.

DThe response is sent twice.

The request is GET /search?q=node+js&page=2. What is logged?

javascript

const url = new URL(req.url, `http://${req.headers.host}`);
console.log(url.pathname, url.searchParams.get('q'), url.searchParams.get('page'), typeof url.searchParams.get('page'));

A/search?q=node+js&page=2 node+js 2 number

B/search node+js 2 string

C/search node js 2 number

D/search node js 2 string

Requests to /users/new hit the wrong handler. Why?

javascript

app.get('/users/:id', (req, res) => res.send(`user ${req.params.id}`));
app.get('/users/new', (req, res) => res.send('new user form'));

AExpress matches routes in registration order, and /users/:id matches /users/new with id = 'new', so the specific route must be registered before the parameterised one.

B:id only matches numbers, so the problem is elsewhere.

CBoth handlers run, and the last response wins.

DExpress sorts routes by specificity automatically.

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