https://github.com/hediet/vscode-debug-visualizer
When debugging JS, there is a nice way to provide visualizations for application specific objects without touching the application code.
Combined with time travel debugging which allows to step backwards, it is really easy to understand complex algorithms:
https://github.com/hediet/vscode-delorean-js-debug
The visualization library is independent and open source. There is also a rust cli and a web playground. I'm very open for contributions! (especially new visualizations)