How to use a custom node version
I'm sure many people have complains about repl.it's node version being old.
What you can to is install node with npm, and specify the start a start script like so "node index.js".
You can also change the package.json file to use whatever node version you want.
You just need to make sure to do
npm install if command isn't found.
You can see the repl for an example.