Use TypeScript parser to read tsconfig.json

[brunolemos]

We have to read tsconfig.json using the ts parser otherwise it will fail, because it may contain things like comments and trailing comma.

One remaining annoyance is that when overriding the json it is removing all comments from the file.

[Timer]

One remaining annoyance is that when overriding the json it is removing all comments from the file.

This isn't too big of a deal when using source control -- you could only stage the lines you care about.

If you can figure something out, please send PR.

[ianschmitz]

@Timer, @brunolemos. Just a heads up that we're missing part of how TypeScript reads in tsconfig.json. If you take a look at my #5519 PR, you'll see how I was also using ts.parseJsonConfigFileContent() which takes care of resolving things like "extends": "./tsconfig.other.json".

Let me know if you want me to make a PR to add that step!

[ianschmitz]

Here's a reference from ts-jest as an example: https://github.com/kulshekhar/ts-jest/blob/13cc4c9b0136030d0aa52dcbe3efb65c48012d70/src/config/config-set.ts#L654

[Timer]

Sure, send a PR please.