I've recently started learning Javascript after a long break, one of the tools I put together for myself is what I'm calling blokz-play, which is an electron app running runkit as seen below. Please note that the gist link below can also be used as a standalone.html file as its not just for use in the Electron App, which is just something I find useful.
Source for index.html for use in the Electron Quick Start is at the gist below
Electron Source: https://github.com/electron/electron-quick-start
What is runkit?
It let's you run node apps. It's pictured above.
https://runkit.com/docs/embed