Quokka.js runs JavaScript and TypeScript with instant feedback. Runtime values are updated and displayed in your editor next to your code, as you type.
A cool piece of software for helping coding and debugging, pro gives extra bits such as lib imports and whatnot. Aussies get a $16 discount, 50% off the remainder. There's also a 30% off "existing user discount", not sure if it stacks!
Price above for individual, org price is $60.50.
I'm sure there are some cases where this would benefit certain dev's but just using Visual Studio Code or https://codesandbox.io/ would suffice for most wouldn't it, both free?