Why Does JSON.stringify Fail to Stringify Error Objects and How Can I Fix It?

JSON.stringify: Can't Stringify Error Objects

When working with web sockets and encountering errors, it's often necessary to pass error messages around. Initially, using JSON.stringify seems like a straightforward solution, but it doesn't properly stringify native Error objects.

Issue:

Attempting to stringify an Error object results in an empty object ({}), indicating that the error's information wasn't captured.

Cause:

The problem lies within the Error object's prototype properties. Key properties like stack and message have their enumerable flag set to false. Consequently, JSON.stringify skips these properties during the serialization process, leaving you with an empty object.

Solution:

To circumvent this behavior, it's necessary to manually extract the Error object's properties using Object.getOwnPropertyNames. These properties can then be passed to JSON.stringify as a replacer function to create a JSON string that includes the error's information:

JSON.stringify(err, Object.getOwnPropertyNames(err))

Alternatively, you can create your own custom error objects with properties that are enumerable, allowing them to be stringified correctly by JSON.stringify.

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