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In NodeJS (same applies to Javascript in browser), why doesn't JSON.stringify(new Error('huh')) print out the Error.message property?

I was debugging some NodeJS code dealing with a file open error and used JSON.stringify() to the Error object, and was surprised when I didn't see the message property.

See https://nodejs.org/api/errors.html#class-error for a list of the fields that include:

  • error.code
  • error.message
  • error.stack

To illustrate, copy the following line into your browser console, or run it as a NodeJS file.

console.log(JSON.stringify(new Error('huh')));
// output is: {}

But the field is there as shown by the following lines of code that display the message field.

console.log(JSON.stringify(new Error('huh'))); // {}
console.log((new Error('huh')).toString());    // Error: huh
console.log((new Error('huh')).message);       // huh

I'm not sure what to search for to find this answer.

SO had the following but they were unrelated to my question:

For completeness, the MDN (browser) Error object is documented here https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error

UPDATE

This question was (rightfully) closed as a duplicate of Is it not possible to stringify an Error using JSON.stringify?.

The short answer to the question is:

The Error class doesn't have ".toJSON" method and the JSON.stringify() method's default way of obtaining properties to process does not include the message field because the message field is not marked as enumerable

Reflect.getOwnPropertyDescriptor(new Error('huh'), 'message').enumerable
// returns false

Credit to @bogdanoff, ASDFGerte and @Jonathan Lonowski (for the duplicate answer)

To get all of the fields of the Error object you can use the following: 

let err = new Error('huh');
console.log('stringify: ' + JSON.stringify(err, Object.getOwnPropertyNames(err)));

From https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error

PatS
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    `Reflect.getOwnPropertyDescriptor(new Error('huh'), 'message').enumerable` – ASDFGerte Jul 12 '22 at 01:41
  • ```JSON.stringify({ name: err.name, message: err.message })``` ? – bogdanoff Jul 12 '22 at 01:51
  • What search terms did you use? The second SO question you link is entirely unrelated, it's [tag:php]. – Bergi Jul 12 '22 at 01:54
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    Error class doesn't have ".toJSON" method that's why. – bogdanoff Jul 12 '22 at 01:54
  • @Bergi, the SO questions I listed were in the suggestions that SO offers when you are writing the question. I didn't know what to search for an answer for this question. – PatS Jul 12 '22 at 02:12
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    @bogdanoff, this is the answer I was looking for. Thank you! I never (till now) knew that stringify() used the toJSON() function on objects. Found https://thecodebarbarian.com/what-is-the-tojson-function-in-javascript.html that explained it! I wish you could open the question and answer it. – PatS Jul 12 '22 at 02:16
  • @ASDFGerte, I didn't realize till I studied what `enumerable` is that I realized you were giving me the answer. Because the `message` field is not enumerable, it doesn't show up in the `JSON.stringify()` output. – PatS Jul 12 '22 at 02:49

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