Install typescript (tsc) globally

You can use npm to install TypeScript globally, this means you can use the tsc command anywhere in your terminal.

To do this, run npm install -g typescript. This will install the latest version (currently 4.2).

Then verify:

ts init

Do this once. Will generate a tsconfig file.

Then all you have to do is tsc to compile all typescript files into js files for the directory.
You can also add watch to it: tsc -w