This is where I practice javascript.

• codeWars
• codefights
• DailyProgrammer
• wesbos 30 days
• interview questions
• hundreds of mdn js questions (JS-exercises, WIP)
• small apps that do stupid things in the browser that will never get deployed

$ git clone 'theurl'
$ cd code-log
$ http-server

If webpack exists, look at its readme and follow the directions there.
Otherwise most of this can be seen through that http-server.
Navigate to an HTML file, then open the dev tools.
If no HTML, I logged the function directly in the IDE.