How to Fix 404 Errors When Calling a NodeJS HTTP Server from JavaScript

Learn how to avoid `404 errors` when using the fetch method in JavaScript to call a NodeJS HTTP Server. This article simplifies enabling CORS for successful server communication.
---

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Calling nodeJS HTTP server from Javascript

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Calling NodeJS HTTP Server from JavaScript

If you've ever tried to interact with a NodeJS HTTP server from your JavaScript code, you may have come across some issues, particularly 404 errors. In this guide, we will address a common scenario where you set up a simple NodeJS server, but encounter problems when trying to call it using the fetch() method. Let’s break down the issue and explore the solution step by step.

The Problem

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

This leads to a 404 Not Found error. What's going wrong here?

The Cause of the Issue

The error stems mainly from a misunderstanding of how to format the URL in your fetch() call. When you use :8081/?q=hi, the colon (:) is incorrectly placed, which results in an invalid URL. Additionally, if your frontend and backend are on different servers (which is common in modern web development), Cross-Origin Resource Sharing (CORS) might also be impacting your request.

The Solution

To resolve this issue, follow these steps:

1. Correct the Fetch Call

Update your fetch() method to use the proper URL format. Here’s how you can do it:

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

2. Enable CORS in Your NodeJS Server

If your frontend and backend are on different origins, enabling CORS is crucial. Here is how to modify your NodeJS server to add CORS support:

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

Explanation of the Code

Access-Control-Allow-Origin: This header allows requests from any origin. For improved security, stack developers often restrict this to only specified origins in a production environment.

Access-Control-Allow-Methods: This header specifies the HTTP methods that are allowed when accessing the server.

Access-Control-Max-Age: This header indicates how long the results of a pre-flight request can be cached.

3. Testing the Server

Once you have made these changes, try calling your server again using the updated fetch request. If everything is set up correctly, you should get a successful response instead of a 404 error.

Conclusion

Encountering 404 errors when trying to call a NodeJS HTTP server from JavaScript can be frustrating, but it's often a simple fix. By ensuring your fetch() call is properly formatted and enabling CORS on your server, you can make smooth requests to your backend without errors. Happy coding!