Quokka provides the ideal scratchpad experience and makes learning, prototyping and testing JavaScript/TypeScript blazingly fast. Runtime values are displayed in VS Code beside your code. Your code runs immediately as you type, on unsaved changes; no need to do anything manually or switch context.
More info on Quokka: https://quokkajs.com
Quokka and other Wallaby.js extensions for VS Code: https://aka.ms/vscodelive/wallaby