What is the reason for my fetch request to generate undefined output?

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There could be several reasons why your fetch request is generating undefined output:

1. Incorrect URL: If the URL you provided is incorrect, then the fetch request will not be able to retrieve the data and will return undefined.

2. No response data: If there is no data returned from the fetch request, then the response will be undefined. This often happens if there is an error with the server or if no data is found.

3. Incorrect parsing of response data: If the response data is not properly parsed, then it may result in undefined output. This can happen if the data returned is not in the expected format (e.g. JSON instead of text).

4. Asynchronous nature of fetch: If the code continues to execute before the fetch request has completed, then the response may not have been processed yet, resulting in undefined output.

To fix the issue, you can try the following:

1. Verify the URL and make sure that it is correct.

2. Check that the server is running and that data is available to be retrieved.

3. Ensure that the data returned from the server is in the expected format and is properly parsed.

4. Use async/await or .then() syntax to ensure that the fetch request has completed before continuing with the code.