Also I tried to use deployJava script for this
I know there is a page http://www.java.com/en/download/installed.jsp which also checks for java. I lioke this page: it doesn't ask some security permissions and displays the java version correctly.You know what the joke is? It uses the deployJava script. I did a quick hack check of the page source (wasn't easy since it refreshes really quickly).
So the question is: how can I check java version on some web-site visitor PC reliably and without showing security permission dialogs?The deployJava script. If you follow in my footsteps you can get the page source of the java.com page as well and "learn" from it. Probably some http sniffer browser plugin or a plugin to get the source of a URL is easier though.