[billpg]

Did they get an entire Python interpreter into JS?

Yes, I know all Turing machines are equivalent so it shouldn't be surprising it was possible but still, cool.

[datastoat]

They use Pyodide, a full Python interpreter in WASM: https://pyodide.org/en/stable/console.html

Pyodide includes manyuseful Python libraries including numpy, pandas, and matplotlib.