Watch Mode ↔ TSC mode to continuously monitor & recompile upon Code change (save)

References

1. run [TSC](tsc_ts-def) in [**_Watch Mode_**](watch-mode) for app.ts ↔ tsc app.ts -w

2. tsc -w (run in project root dir) ↔ enter Watch Mode in root project dir to watch changes for all .ts files