Theoretically we would be fine to leavejsx untouched & remove that first piece of the ternary, however, that relies on the assumption that the user does have atsconfig.json and that it's correctly set.

Conditionally addingjsxFactory (andjsxFragmentFactory) is enough to quell the errors we were getting in the linked issue, but when using--jsxImportSource with TS, thetsconfig.json will need to have different values. While users in all likelihood will have atsconfig.json that's correctly configured in that case, if they do not, their typings will containany where JSX references should be.

Setting these configurations ourselves, at least as defaults, allows us to make fewer assumptions about users' configs that are external to Microbundle (and hopefully will raise fewer issues).

should this bepreserve, orreact?

preserve should be correct, though from my quick tests I don't think it makes a difference either way.

preserve is to be used when having another tool transpile JSX (e.g., babel), which is what we do.react on the other hand has TSC transpile it itself.TS Docs

I think, at best,react would do nothing, and at worst, it'd slow down type generation due to trying to handle JSX which we don't need. No one's raised any issues regardingpreserve so I'd assume it's fine.

Edit: Depends on what we want, I suppose. I'd prefer to have TS handle as little as possible andpreserve is already the default behavior. I didn't originally realize we did have TS handle JSX.