[Javascript] Detecting Java (JRE) through JavaScript

[JS Student]

Hi,

I have a java applet on my webpage. It works on most browsers but on
certain broswers (like IE7) that have JRE disabled by default, it
doesn't work.

I want to detect whether JRE is installed or not and if it is
installed, is it enabled or disabled. Can this be done in JS? If so
can someone please tell me how?

Thanks.