Скачать или смотреть How to Redirect After a fetch() Call Using Node.js and Express

Learn how to properly handle redirections in your JavaScript applications using `fetch()` and Node.js Express. This guide explains the issue with CORS and how to implement effective redirection strategies.
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How to Redirect After a fetch() Call Using Node.js and Express

Web development often requires handling data from server requests, and one common requirement is to redirect users after a POST request. If you're using Node.js and Express, you might run into issues, particularly related to CORS (Cross-Origin Resource Sharing). In this guide, we’ll explore a precise problem regarding redirection after a fetch() call and how to implement a solution effectively.

Understanding the Problem

You are attempting to redirect users to another URL after a POST fetch() call. Here’s a simplified version of what your code looks like:

[[See Video to Reveal this Text or Code Snippet]]

On the server-side, you have a basic Express endpoint set up to redirect requests:

[[See Video to Reveal this Text or Code Snippet]]

However, you're running into a CORS-related error when redirecting to google.com. The error message states:

[[See Video to Reveal this Text or Code Snippet]]

Why Is This Happening?

The issue you're facing is linked to the behavior of AJAX calls, such as those made with the fetch() API:

AJAX calls do not change the browser display. They return the result back to your JavaScript without altering the current page.

If the server sends a redirect response (like a 302 status code), your front-end JavaScript (when using fetch()) will not automatically change the window's location.

Instead of the browser following the redirect directly, you have to explicitly instruct it to do so.

Solution: Using window.location

To achieve the desired behavior, you can handle the redirect within your JavaScript. Here’s how you can do this:

Step 1: Modify Your Fetch Response Handling

Instead of solely relying on fetch() to redirect the user, utilize the response object from the server to read the status code and the location header. You will manually set the window.location:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Ensure CORS is Configured Properly

Make sure your Express app has CORS properly configured to allow the desired requests. You can use the cors middleware, which you already have, but consider whether further configuration is necessary based on your app’s requirements.

Benefits of This Approach

Control Over Redirection: You have complete control over how the application responds to users after fetching data.

Consistent Behavior: Ensures a consistent and user-friendly experience, allowing for the necessary redirections to occur.

Conclusion

Handling redirects after a fetch() call in a Node.js Express application requires a careful approach, particularly when dealing with CORS. By utilizing the window.location property after checking the server’s response, you can effectively navigate users to the desired URLs without falling victim to common pitfalls like CORS errors.

With this understanding, you can enhance your web applications and ensure a seamless user experience. Happy coding!