Скачать или смотреть Resolving the SyntaxError: Unexpected token ' ' Issue in React When Fetching API Data

Learn how to fix the common error `SyntaxError: Unexpected token ' '` when fetching data from APIs in React, specifically with OpenWeatherMap.
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This video is based on the question https://stackoverflow.com/q/75109361/ asked by the user 'Aadil Khatri' ( https://stackoverflow.com/u/19250903/ ) and on the answer https://stackoverflow.com/a/75110564/ provided by the user 'Aadil Khatri' ( https://stackoverflow.com/u/19250903/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Troubleshooting SyntaxError: Unexpected token '<' in React API Calls

When developing applications using React, you may encounter various errors that can interrupt your workflow. One such common issue is the SyntaxError: Unexpected token '<', "<!DOCTYPE "... is not valid JSON. This error typically occurs when the response from the API you are fetching data from is not in the expected JSON format. Let's dive deeper into understanding why this happens and how to fix it.

Understanding the Problem

In a typical React application that fetches data from an API, you expect to receive a JSON response. However, during the process of fetching data, you might encounter HTML instead of JSON. This usually leads to the error we mentioned:

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Possible Cause

The main reason why this error arises is that the API URL you are trying to access is incorrect or missing the required protocol (HTTP/HTTPS). As a result, instead of a JSON response, you receive an HTML document (such as a 404 error page), which begins with the <!DOCTYPE> tag. Here’s how to diagnose and correct this issue.

Steps to Resolve the Issue

1. Check Your API URL

In the provided code, the issue lies in the declaration of the WEATHER_API_URL. The URL is missing the necessary https:// prefix, which leads to an incorrect API endpoint. Here’s the problematic line:

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

2. Update Your API URL

To fix this error, you need to prefix the URL with https://. The corrected line should look like this:

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This simple change tells the application to correctly access the OpenWeatherMap API over the secure HTTPS protocol.

3. Validate API Key and Request

Ensure that your API key is valid and that your API request includes it as a query parameter. The correct format for the fetch call should be as follows:

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4. Test the Response

After making these changes, test the API call directly in your browser to verify that the endpoint returns a JSON response instead of an HTML document. For instance:

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5. Handle Errors Gracefully

As you work with API calls, it’s important to handle potential errors gracefully. You can do this by checking the response status before attempting to parse it as JSON:

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

Conclusion

The SyntaxError: Unexpected token '<' can be a frustrating error when fetching data in your React application. By ensuring your API URLs are correctly formatted and handling API requests and responses with care, you can avoid this issue in the future. Always remember to validate your requests and test them directly in your browser to confirm expected behavior.

If you’ve made the changes outlined in this post and are still facing issues, feel free to reach out or check for additional configuration possibilities related to your setup. Happy coding!