Javascript as a language originated in the browser as the primary scripting language of the web. However today you can create anything from server-side apps to controlling IoT devices with Javascript. Because Javascript was originally for the browser most of the tutorials you will find have some sort of focus on how to integrate Javascript with the browser. To use Javascript for SoundFlow you will need to skip any of that information.

We are trying hard to find the best Javascript learning resources that are completely independent of which context the code runs in (browser, nodejs, etc.) to make it less confusing. But basically you'll need to skip parts where they're talking about HTML and putting code inside <script> tags etc.