Run the TypeScript Compiler (TSC).
Open a terminal window in the root of the application folder and enter:
npm run tsc
This script set the compiler watch option (-w) so the compiler stays alive when it's finished. It watches for changes to the .ts files and recompiles them automatically.
Leave this command running in the terminal window.
You can stop it anytime with Ctrl-C.
Open another terminal window in the root of the application folder and launch live-server by entering:
npm start
live-server loads the browser, serves the HTML and JavaScript files and detects changes to the files and refreshes the browser page automatically.
Keep live-server running in this terminal window.
You can stop it anytime with Ctrl-C.