`NaN` quietly breaks all data

[remy]

I've just found that if I return NaN (unwittingly), it causes the entire response to become empty.

I've not looked at the Go source (and though I can probably read it, I've not programmed anything in anger with Go, so don't entirely trust myself), but my guess would be that the conversion is quietly failing and causes all data to be ejected.

Here's how to replicate in a script.mjs:

export const config = {
  url: 'https://example.com',
};

export default function () {
  return Array.from({ length: 10 }).map(() => ({
    a: 'test',
    b: NaN,
  }));
}

Result:

$ flyscrape run script.mjs
[

]

If I wrap the return value in a serialise/deserialise then it works again (but only because NaN gets mapped to null).

[philippta]

Thanks for reporting. The issue got fixed in #21 by running the return value through the JavaScript serialise/deserialise.

[philippta]

(but only because NaN gets mapped to null).

To give a bit more context:

• JSON does not permit serialization of NaN, +Inf and -Inf as per RFC4627 2.4.
• The Go authors decided to not handle these values gracefully, but return errors instead.
• JavaScript does not strictly comply to the spec and replaces these values with null instead.