I was wrong, It request the scripts even if the parent container is hidden. I used tool called Fiddler to monitor the Http request.
Fiddler can be downloded from here http://www.fiddler2.com/Fiddler2/version.asp . Its nice tool to know how browser is requesting the server.
Its nice tool to debug at cleint side.
<script src=http://some_domain.com/some_java_script.js >
There are so many tools available to monitor http / https request like Http Viewer