res.redirect for redirections in Express - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What happens when res.redirect is called with a relative URL?

Consider this Express route handler:

app.get('/old-page', (req, res) => {
  res.redirect('/new-page');
});

What will the browser do when a user visits /old-page?

Express

app.get('/old-page', (req, res) => {
  res.redirect('/new-page');
});

A The browser will navigate to 'http://new-page' as a full URL.

B The browser will stay on '/old-page' and display the content of '/new-page' without changing the URL.

C The browser will throw an error because the URL is relative.

D The browser will navigate to the absolute path '/new-page' on the same domain.

💡 Hint

Think about how relative URLs starting with '/' behave in web browsers.

When res.redirect is called with a URL starting with '/', it tells the browser to go to that path on the current domain. So the browser changes the URL to '/new-page' and loads that page.

📝 Syntax

intermediate

Which res.redirect usage is syntactically correct?

Which of the following Express code snippets correctly uses res.redirect to redirect to 'https://example.com'?

A res.redirect('https://example.com');

B res.redirect('301', 'https://example.com');

C res.redirect(301, 'https://example.com');

D res.redirect(redirectUrl = 'https://example.com');

💡 Hint

Check the official Express documentation for res.redirect method signatures.

The correct syntax to specify a status code and URL is res.redirect(statusCode, url). The status code must be a number, not a string. Option C uses 301 as a number, so it is correct.

🔧 Debug

advanced

Why does this code throw a server error?

Look at this Express route:

app.get('/start', (req, res) => {
  res.redirect('/middle');
  res.send('Done');
});

Why does this code cause a server-side error?

Express

app.get('/start', (req, res) => {
  res.redirect('/middle');
  res.send('Done');
});

A Calling res.send after res.redirect causes an error because the response is already sent.

B res.redirect does not send a response, so res.send is needed to complete it.

C Express requires next() to be called after res.redirect to complete the redirect.

D The redirect URL '/middle' is invalid and causes the redirect to fail silently.

💡 Hint

Think about what happens when you try to send two responses for one request.

Once res.redirect sends a response, calling res.send again causes an error because the response is already finished.

❓ state_output

advanced

What is the HTTP status code sent by default with res.redirect?

Given this Express code:

app.get('/go', (req, res) => {
  res.redirect('/target');
});

What HTTP status code will the client receive?

Express

app.get('/go', (req, res) => {
  res.redirect('/target');
});

A 302 (Found)

B 308 (Permanent Redirect)

C 307 (Temporary Redirect)

D 301 (Moved Permanently)

💡 Hint

Check the Express documentation for the default redirect status code.

By default, res.redirect sends a 302 status code, which means the resource is temporarily found at a new location.

🧠 Conceptual

expert

How does res.redirect handle absolute URLs with different domains?

If you use res.redirect('https://otherdomain.com/page') in Express, what happens in the browser?

A Express blocks redirects to external domains for security and throws an error.

B The browser navigates to the full URL 'https://otherdomain.com/page' on a different domain.

C The browser treats it as a relative path and navigates to '/https://otherdomain.com/page' on the current domain.

D The redirect is ignored and the original page remains loaded.

💡 Hint

Think about how browsers handle full URLs in HTTP redirects.

When res.redirect is given a full URL with a different domain, it sends a redirect response with that URL. The browser then navigates to that external domain.