How can I stop JavaScript from being cached during development?
I'm assuming you have to clear caches because your JS file is being aggregated? Can't think of a different reason.

That has absolutely nothing to do with how you add your JS file (Most of what you tried shouldn't even work, use #attached][library).

Instead, it depends on the separate settings to aggregate JS or not. You can find them on the Performance settings page. Aggregation is also automatically disabled if you use the provided sites/example.settings.local.php as your settings.local.php, which I strongly recommend when doing development, also for the other things it does like enable verbose error logging and disabling render caching (but keep in mind to always test your code with render caching too).