Скачать или смотреть Troubleshooting the Uncaught SyntaxError: Unexpected token ' ' Error in Node.js with RequireJS

Learn how to resolve the `Uncaught SyntaxError: Unexpected token ' '` error in Node.js projects using RequireJS by implementing proper server routing.
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This video is based on the question https://stackoverflow.com/q/63131402/ asked by the user 'Yu Zhang' ( https://stackoverflow.com/u/3999025/ ) and on the answer https://stackoverflow.com/a/63133240/ provided by the user 'Lennholm' ( https://stackoverflow.com/u/2236921/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Troubleshooting the Uncaught SyntaxError: Unexpected token '<' Error in Node.js with RequireJS

If you're developing a Node.js project utilizing RequireJS and suddenly encounter the pesky error Uncaught SyntaxError: Unexpected token '<', don’t worry; you’re not alone. This issue often indicates a misconfiguration in your server routing, specifically when the server is unable to locate the required JavaScript files. In this guide, we will explore the root cause of this error and how to fix it effectively.

Understanding the Error

When you try to serve a JavaScript file, but the server accidentally serves an HTML file instead (often the main index.html file), the browser tries to parse the HTML as JavaScript. As a result, it encounters an unexpected token, leading to the Uncaught SyntaxError: Unexpected token '<' error in the developer console.

Common Scenario

In a simple Node.js project structured like the following:

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

Your index.html file attempts to load require.js from the scripts directory. If your server does not handle requests for this file correctly, it will not be found, leading to the error mentioned.

Identifying the Problem

In your server.js file, the issue arises from two main problems:

Incorrect URL Handling: The server is currently set to respond only to requests that match the root path (/). All other requests return the same response intended for the index.html.

Improper Comparison: The if statement is using an assignment (=) instead of a comparison (===), which means that it always evaluates to true.

The Code Snippet

Here is the relevant portion of your server code that needs attention:

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

This line should compare, not assign, to work correctly.

The Solution: Fixing the Server Logic

To resolve these issues, you can update your server.js file with a more robust routing logic. Here’s how to modify your server to correctly respond to requests for JavaScript files in the scripts directory:

Updated Server Code

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

Explanation of the Changes

Fixed the Comparison: The conditional check was updated to use === to ensure it’s checking for equality.

Added JS File Handler: An additional conditional statement was added to handle requests for any JavaScript files in the scripts directory. This ensures correct file retrieval.

File Path Construction: The path to the requested JS file is constructed using req.url, properly allowing the server to read the correct file from disk.

Testing Your Setup

After making these changes, run your server again by executing node server.js and navigate to localhost:5000. The Press key to continue message should display without the error, indicating that your JavaScript files are being served correctly.

Conclusion

Encountering the Uncaught SyntaxError: Unexpected token '<' error can be frustrating, but with the proper routing setup in your Node.js server, it can be easily resolved. By ensuring your server handles different paths correctly, you can serve your JavaScript files without issues. Happy coding!