Allow javascript (or typescript) config file

Suggestion

I suggest allowing a tsconfig.js or tsconfig.ts as an optional alternative to tsconfig.json.

Use Cases

What do you want to use this for? Primarily to add comments to the tsconfig file. What shortcomings exist with current approaches? JSON does not allow comments. You can’t even hack in comments by adding fake fields like "_explanationOfTypeRoots", as the build complains about unknown compiler options and stops.

Examples

Many tools and frameworks allow javascript config files. Jest, for example. jest --init produces a heavily commented config file, which is very useful for beginners.

[CEbbinghaus]

We are not accepting PRs to turn config into an executable thing. This opens up an enormous can of worms (is it safe to run this? what dependencies does the config file have? what does the config file assume about its environment?) that we’d prefer remain closed.

This makes little sense to me when so many other JS libraries support them.

#39441 names a few but there are plenty more that all allow this behaviour. If every one of them had a discussion on the same security concerns, then wouldn’t looking through their discussions yield the information needed to implement it in a safe and responsible fashion?

[alexmiddeleer]

Oh, nice! I was under the impression that comments were not allowed in JSON, but it makes sense that someone would write a parser that allows them. Thank you for your response, I am closing the issue because I no longer think this feature is necessary.