Whenever we do client side coding, we are bounded by the browser rules. If browser allow user the option to turn off Javascript or even Java, basically web-pages with Javascript cannot run and so does Java Applet.
But at current age and time, I would presume most user will enable Javascript and Java.
A classic example would be local banks in Singapore all uses Java Applet for the login page, so if you want to do internet banking, you got to install and enable Java isn't it ? I call such design as 'implicitly' forcing users to install and turn on Java.
I have not found a case where Javascript is strictly needed. Anyone want to give example of how companies/institutions "implicitly" forcing users to turn on Javascript ?