Add support for React Native.

[dmitrizagidulin]

Add support for React Native (RN-specific support for TextEncoder, crypto).
Shouldn't affect any existing code.

[davidlehn]

How can this be tested? Some sort of test like what is done with karma should be added so we know this works and regressions are caught over time.

[dmitrizagidulin]

@dlongley @davidlehn - I updated this PR with what we discussed (moved the TextEncoder and crypto dependencies to an external polyfill library, leaving just the package.json "react-native" mapping section).

[dlongley]

LGTM -- @davidlehn?

[davidlehn]

This looks like a fairly simple solution, thanks. I hope externalizing the fixes is ok from a user perspective. I do still have a concern about how to test this. I'm guessing that would add quite a bit of complexity if done here. Is it tested somewhere else indirectly?

[dmitrizagidulin]

This looks like a fairly simple solution, thanks. I hope externalizing the fixes is ok from a user perspective. I do still have a concern about how to test this. I'm guessing that would add quite a bit of complexity if done here. Is it tested somewhere else indirectly?

Yeah, there's no easy way to test it here in this lib. If it's any comfort, it'll be constantly tested downstream, in the DCC mobile wallet.

[davidlehn]

In practice will people be able to determine the polyfill requirement? If someone installs a higher up lib/app that indirectly uses rdf-canonize, and they see related missing polyfill problems, will it be obvious to look at the README here to find the solution? Does it fail at runtime or in a pre-processing step?

I think there was talk of having code somewhere to throw errors if the required APIs were missing. Ideally would like to avoid that since it adds bloat that will never be used in properly setup app.

[dmitrizagidulin]

In practice will people be able to determine the polyfill requirement? If someone installs a higher up lib/app that indirectly uses rdf-canonize, and they see related missing polyfill problems, will it be obvious to look at the README here to find the solution? Does it fail at runtime or in a pre-processing step?

I think there was talk of having code somewhere to throw errors if the required APIs were missing. Ideally would like to avoid that since it adds bloat that will never be used in properly setup app.

Agreed, yeah (and in any case, we can handle that question in a separate PR). My strategy is -- I'm going to add these usage examples in downstream libraries (the VC lib etc), which is the most likely place devs will encounter this lib.

[dmitrizagidulin]

@davidlehn Sounds like comments have been addressed, can we merge this? (into the 3.4.0 branch?)

[davidlehn]

Manually fixed conflict and merged. Thanks.