[rootlocus]

But TS is not valid JS and nobody uses TS because they can write JS in a file with a different extension. You also get 0 benefit from running `tsc` on a JS file. You could argue that C is valid C++ so there's no reason to discern them either.

[wiseowise]

> You could argue that C is valid C++ so there's no reason to discern them either.

Only up to C90, and even modern C++ doesn’t fully implement modern C.

JS is a valid TS.