Typescript return string or undefined?

[dylanqian29]

Hi, I have read through your package and source code, and I'm wondering in what situation the serialize method will return undefined. Based on the type definition that is shown in this link, it seems like the output for typescript is shown as string | undefined.

However, when I compare this to the javascript implementation in this file, it appears this method can only return as a string.

Thank you for your contribution! :)

[aren55555]

We'd be happy to contribute a fix PR, but just wanted to get your thoughts on this in case we were missing anything!

[erdtman]

I did some tests and could find 2 cases where it returned undefined.

• if the input is undefined
• if the object has a toJSON method that returns undefined
  Not sure what the RFC says on this topic, need to check.

@cyberphone do you know?

[aren55555]

I wonder if there's a way to more generic TS implemenetnation for this method such that based on the input type the expected outputs change.

For example, if I passed in an object {...} or an array [...] the only possible output would be a string; conversely if I pass in undefined the only possible output is undefined... 🤔

I guess the default JSON.stringify is typed the same as this method so perhaps this isn't really a problem and just something we should handle in our application code.

[cyberphone]

Hi @erdtman, the RFC does the assumption that the data to be canonicalized is JSON-serializable (in a generic fashion rather than JavaScript-specific), which excludes undefined since it is not a part of JSON. The JavaScript sample in the RFC is as we have seen before somewhat simplistic.

I don't have any opinion on things that are platform-specific but if there was a JSON.canonify(), it would surely follow JSON.stringify().