Express req.xhr Property

Posted in Express Tutorial

Updated on Feb 18, 2024

By Mari Selvan

👁️ 22 - Views

⏳ 4 mins

💬 1 Comment

Photo Credit to CodeToFun

🙋 Introduction

In web development, distinguishing between regular HTTP requests and AJAX (Asynchronous JavaScript and XML) requests is crucial for delivering a seamless user experience.

Express.js provides the req.xhr property, allowing you to identify AJAX requests within your route handlers and middleware functions.

This guide will delve into the syntax, usage, and practical examples of the req.xhr property in Express.js.

💡 Syntax

The syntax for using the req.xhr property is simple:

syntax.js

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if (req.xhr) {
  // Code to handle AJAX request
} else {
  // Code to handle regular HTTP request
}

❓ How req.xhr Works

The req.xhr property in Express.js is a boolean value that indicates whether the request was made with XMLHttpRequest (commonly used in AJAX requests). When req.xhr is true, it signifies an AJAX request, and when false, it denotes a regular HTTP request.

example.js

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app.get('/api/data', (req, res) => {
  if (req.xhr) {
    // Respond to AJAX request
    res.json({ data: 'AJAX response' });
  } else {
    // Respond to regular HTTP request
    res.send('Regular HTTP response');
  }
});

In this example, the route /api/data checks req.xhr to differentiate between an AJAX request and a regular HTTP request, responding accordingly.

📚 Use Cases

Dynamic Content Loading:

Utilize req.xhr to load partial content for AJAX requests, enhancing the user experience with dynamic updates.

example.js

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app.get('/dynamic-content', (req, res) => {
  if (req.xhr) {
    // Load partial content for AJAX requests
    res.render('partials/dynamic-content');
  } else {
    // Render full page for regular HTTP requests
    res.render('full-page');
  }
});

Conditional Responses:

Customize responses based on the request type using req.xhr, providing different formats for AJAX and regular requests.

example.js

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app.get('/api/user/:id', (req, res) => {
  const userId = req.params.id;
  const userData = getUserData(userId);

  if (req.xhr) {
    // Respond with JSON for AJAX requests
    res.json(userData);
  } else {
    // Render user profile page for regular HTTP requests
    res.render('user-profile', { userData });
  }
});

🏆 Best Practices

Consistent API Responses:

Ensure consistency in API responses by using req.xhr to format JSON responses for AJAX requests.

example.js

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app.get('/api/data', (req, res) => {
  if (req.xhr) {
    // Consistent JSON response for AJAX requests
    res.json({ data: 'AJAX response' });
  } else {
    // Handle non-AJAX requests as needed
    res.send('Regular HTTP response');
  }
});

Graceful Degradation:

Implement graceful degradation by providing fallbacks for non-AJAX scenarios, ensuring a functional user experience in all situations.

example.js

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app.get('/fallback', (req, res) => {
  if (req.xhr) {
    // Provide AJAX-specific content
    res.json({ message: 'AJAX response' });
  } else {
    // Fallback for non-AJAX requests
    res.send('Fallback content for regular HTTP request');
  }
});

🎉 Conclusion

The req.xhr property in Express.js is a valuable tool for identifying AJAX requests and tailoring your server's responses accordingly. By understanding how to use req.xhr effectively, you can enhance your Express.js applications with dynamic and responsive behavior.

Now, equipped with knowledge about req.xhr, go ahead and implement AJAX-aware features in your Express.js projects!