fix(js): free native strings

[genaris]

Not completely sure if it's the right approach (especially in react-native) but here is a simple attempt to free strings automatically in JS wrappers before returning to the caller, as discussed in #236.

[TimoGlastra]

This doesn't include the RN implementation yet right?

[TimoGlastra]

Is a buffer also copied and not a ref?

[genaris]

I've just done an update there because when creating an Uint8Array from a Buffer (this case in line 727) simply a new view is created, meaning (if I understand correctly) that no data is copied.

So I think it is safer to do this buffer free right after doing the text decoding and outputting to a string (which effectively copies the data).

[berendsliedrecht]

It would depend on how ffi-napi ref-napi handles this. It seems to me that they copy the data, but I haven't checked the code, yet.

[berendsliedrecht]

LGTM. TypeScript 5.2.2 has been released so we can use the new using declaration to probably make it even better. This could even be done in the shared part of the library fixing it for Node.JS and React Native

[genaris]

This doesn't include the RN implementation yet right?

I couldn't test it deeply but I've updated those template createReturnValue functions related to strings (char *) and buffers (ByteBuffer) to call these clean up functions, so the fix should work also for RN.

[genaris]

LGTM. TypeScript 5.2.2 has been released so we can use the new using declaration to probably make it even better. This could even be done in the shared part of the library fixing it for Node.JS and React Native

Absolutely! I was looking at the release notes and using seems really promising for our exact use case (here and in aries-askar wrapper as well). But having it available in TS does automatically mean that we can use it in Node.js and React Native? I've seen that the related proposal is at stage 3 (candidate). Does that mean that it will take some time until JS engines like V8 or Hermes adopt it officially?