If the `"files"` and `"include"` are both left unspecified, the compiler defaults to including all TypeScript (`.ts`, `.d.ts` and `.tsx`) files in the containing directory and subdirectories except those excluded using the `"exclude"` property. JS files (`.js` and `.jsx`) are also included if `allowJs` is set to true.

If the `"files"` or `"include"` properties are specified, the compiler will instead include the union of the files included by those two properties.

Files included using `"include"` can be filtered using the `"exclude"` property.

However, files included explicitly using the `"files"` property are always included regardless of `"exclude"`.