Add options to choose JSX file extension .js or .jsx

[frogcjn]

I want to keep jsx in the file content, so I choose:

        "jsx": "preserve"

but the generated file has jsx extension and ReactNative refuse to recognize this extension.

So there needs an option to let JSX format file using js extension.

[dum3ng]

Yeah I met the same problem.
I would like to see the compiled file with jsx expression because that's clear but I do not want the .jsx extension. React Native just does not recognize them.

[RyanCavanaugh]

I'd propose an option preserveJs that retains JSX expressions but computes the filename as .js. This should be a fairly easy change if someone wants to send a PR for it

[jbaxleyiii]

@RyanCavanaugh I'd love to take this! Can you give me any other direction?

[jbaxleyiii]

Actually it looks like https://github.com/Microsoft/TypeScript/pull/9864/files targets this?

[basarat]

I'm a big fan of keeping jsx out of .js files :) but thats just my opinion and I haven't done react native 🌹

[ivogabe]

I think this can be closed, implemented in #13636.