Generally speaking, it makes no difference where a Javascript file is served from. The Javascript code will be executed in exactly the same way, since the Javascript interpreter lives on the client-side.
The only difference would be when you are making ajax requests from your Javascript. Some browsers (chrome, firefox) prevent ajax calls to local files, even when the request is coming from a local file, though this can be disabled. When using a local server however, this would not be an issue, as the requests are treated like normal HTTP requests.