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Complete Guide to Express Response Objects

Deepika
Express Response Objects

In Express.js, the response object (res) plays a crucial role in crafting server responses to client requests. It provides a range of methods and properties that allow you to control the response behavior and send appropriate data back to the client.

This complete guide will walk you through the intricacies of Express response objects, empowering you to create effective server responses.

Setting Response Status Codes:

Response status codes indicate the outcome of a request. Express allows you to set the status code using the res.status() method. Here’s an example:

app.get('/users', (req, res) => {
  // Perform operations to fetch user data
  if (/* Error occurred */) {
    res.status(500).send('Internal Server Error');
  } else {
    res.status(200).json(users);
  }
});

Sending Data in Responses:

Express provides several methods to send data back to the client. The res.send() method is versatile and can handle various types of data. Here’s an example:

app.get('/hello', (req, res) => {
  res.send('Hello, world!');
});

Redirecting the Client:

When you need to redirect the client to a different URL, Express offers the res.redirect() method. Here’s how you can use it:

app.get('/login', (req, res) => {
  if (/* User not logged in */) {
    res.redirect('/auth/login');
  } else {
    res.redirect('/dashboard');
  }
});

Setting Response Headers:

Response headers provide additional information about the server’s response. Express allows you to set headers using the res.set() method. Here’s an example:

app.get('/download', (req, res) => {
  res.set('Content-Type', 'application/pdf');
  res.set('Content-Disposition', 'attachment; filename="document.pdf"');
  // Send the file data or stream to the client
});

Sending JSON Responses:

JSON is a commonly used data format for APIs. Express simplifies sending JSON responses using the res.json() method. Here’s an example:

app.get('/api/users', (req, res) => {
  // Fetch user data from the database
  res.json(users);
});

Conclusion

Understanding Express response objects is essential for crafting effective server responses in your Express.js applications.

In this comprehensive guide, we explored setting status codes, sending data, handling redirects, setting headers, and sending JSON responses. By harnessing the capabilities of the response object, you can create powerful and dynamic server responses. Enhance your web applications with Express response objects today!

FAQs

Yes, Express supports following request objects too res.append, res.attachment, res.cookie, res.download.

You can read our article Basic Routing with ExpressJs

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