I'm a big fan of reading source code if I can't figure stuff out. PHP already works pretty well for looking at the source of Flarum on your local machine. But, for the longest time, I couldn't figure out how to link the javascript files. I searched a bunch and couldn't come up with anything. Finally, I found some jsconfig.json settings for Visual Studio Code that properly links your imports to the local Flarum source. Just create a jsconfig.json file in your js folder and copy the settings from this github gist. The only catch is you need to run composer install in your extension folder but I imagine a lot of you already do that.
If you have any other useful Flarum VS Code dev tips feel free to let me know.
