Consider JSON5 for config (e.g. trailing commas)

[aseemk]

TypeScript Version: 2.0.9

Hi there,

Great work on TypeScript so far! A lot of thought has clearly been put into it, particularly the developer experience, so thank you.

A nice example is that tsconfig.json allows comments. This is really valuable.

I'm curious, though: instead of stripping out comments manually, would you guys be open to considering JSON5 for achieving both that as well as other niceties?

Trailing commas would be the big one to me: when I'm experimenting with new compiler options, that keeps tripping me up. More flexible quoting would also be nice, but less of a big deal.

Big disclaimer: I'm the original author of JSON5, though others maintain it these days, and it's reasonably popular on its own. (E.g. used by Babel and React Native for their config files.)

Thanks for the consideration. Cheers.

(Edit: FYI I just made a similar request for tslint.json: palantir/tslint#1721)

[mhegazy]

We do have a JSON parser already :) , so no need to use external libraries.

[aseemk]

Cool, so consider this a request for at least trailing commas then. =) Thank you!

[aluanhaddad]

Then every tool will need to implement this as well in order to parse the config file.
If that's the route to go down it's worth considering a clean break from the format http://vpzomtrrfrt.github.io/DSON/

[mhegazy]

The compiler will allow for better error recovery, and will report JSON errors as warnings. users could choose to ignore them, and then other tools will not work. but at least they can get useful error messages, specially in the IDE.

[ikokostya]

Eslint supports configuration files in JavaScript format. I think this is good solution, because:

• It's simple. You don't need learn new format.
• You can add comments, trailing commas or any other logic (e.g. dynamically build includes).
• Don't need additional libraries for parsing.
• Clear error messages for invalid js (unlike JSON.parse()).