There is no specific option to disable caching only for JavaScript, you will have to disable caching entirely.
FireBug has an option to disable the browser cache on the Network tab's drop down menu.
Best strategy is to design your site to build a unique URL to your JS files, that gets reset every time there is a change. That way it caches when there has been no change, but imediately reloads when any change occurs.
You'd need to adjust for your specific environment tools, but if you are using PHP/Apache, here's a great solution for both you, and the end-users.
http://verens.com/archives/2008/04/09/javascript-cache-problem-solved/
There are pros and cons to the last two solutions posted, but they're both IMHO great solutions.
You may or may not want your session ID embedded in your url like that for tighter security. But in development that shouldn't matter, but what if you forget to remove it? Also does that really work? Wouldn't you need something like a sequential number generator (hit count stored in the session, or maybe even just if 1 then 0, if 0 then 1)?
Adding a session id (or whatever sequencer) means you need to remember to add it to every resource you don't want cached. On the one hand that's better because you can just include your session id with just that resource you're actively developing and testing. On the other hand, it means you have to do that and you have to remember to remove that for production.
Modifying the vhost.conf or the .htaccess file does the trick nicely without the need to remember to add and remove the session id. But the downside is performance of all js and css resources will be affected, and if you have large files, that's going to slow you down.
Both seem like great, elegant solutions -- depends on your needs.