Add new targets to aes-js exports for smaller bundles

[jmrossy]

Summary

The json-wallet package uses aes-js, which adds ~40Kb to ethers projects bundle size. Adding a browser-specific target to aes-js could reduce that to near 0 for browser bundles.

Details

This may be more relevant to the aes-js lib but I think discussion here highlights the value of the change. And also @ricmoo created both libs anyway 😉

The aes-js lib could be split based on the target environment in order to significantly reduce the size for browser targets, where size matters most. This can be done by creating a new browser target to the package.json
which points to a small shim instead of the main lib. The shim would wrap the browser-native crypto.subtle api. Note, the exports package.json field would work too, either way.

[jmrossy]

I should add, if folks are generally supportive of this idea I'm happy to make the needed changes to aes-js and ethers (if any are needed there).

[ricmoo]

I think the subtle APIs are all Promise-based, no? Which unfortunately means they cannot be used in most places they are needed in ethers… :s

I am planning to refactor aes-js into TypeScript and use modules (and remove the encoding libs; there are better libraries in ethers for people who need that ;)) so a thinner subset of features can be pulled in. :)

[jmrossy]

They are promise-based yes. Sorry didn't consider that aspect but if they need to be sync then actually the subtle APIs won't be a good fit.

[ricmoo]

I also think they are only available in a secure context? Which would break them entirely for people using local tools and in development environments.

But I’m not sure about that, and would require some experimentation to see where they do and don’t work…

[jmrossy]

I can confirm I've used the subtle APIs when dev-ing on localhost in Safari, Firefox, and Chrome without any issues.