Why Am I Getting a \'SyntaxError: Unexpected end of input\' When Using \'no-cors\' Mode in Fetch Requests?

Error Handling in Fetch Requests with 'no-cors' Mode

When attempting to fetch data from an API and setting the mode option to 'no-cors', as suggested in certain online discussions, developers can encounter an error that states:

Uncaught (in promise) SyntaxError: Unexpected end of input for return response.json()

While this error message provides little insight into the actual cause, it can be attributed to a lack of understanding of the 'no-cors' mode.

According to the error message, "... if an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled." However, in this scenario, since the intention is to access the response data, an opaque response is not suitable.

Addressing the Issue

To resolve this error, the 'no-cors' mode should be omitted, and the API server should be configured to grant permission through CORS. This involves setting appropriate headers such as 'Access-Control-Allow-Origin' in the server's response to enable cross-origin requests from the client.

In summary, when encountering this error while fetching data with 'no-cors', developers should consider the following recommendations:

• Avoid using the 'no-cors' mode.
• Configure the API server to implement CORS permissions.

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