Javascript is just client based, you can not use it on the server side. Javscript is quick neat and clean and does not need the applets to run.
I can not code in Java, just many other languages. Javascript, you can create objects and there is a question about that near the middle of the forum list.
Javascript can detect all mouse movements, almost every key on the keyboard (not the print screen key), detect clicks, focus, etc.
Very easy open source code that anyone can learn, esp. if the person knows c or c++.
Biggest differnce between javascript and applets is, none of that class stuff needs to be loaded. Javascript tajes milliseconds to load while applets take seconds upon seconds.
Now applets have some features that are not supported well in all the browsers. Text display is one of them. IE supports cerain filters in the browser and Netscape doesn't. That is why it makes it hard in Javascript.
everyone that does javascript/DHTML knows these lines:
if(document.all){}
if(document.getElementById){}
if(Document.layers){}
look at any good site:
http://www.dynamicdrive.com http://www.javascriptkit.com or even mine at the bottom, you can see what javascript can do.
Now that I probably made no sense and bored you to bits, I will end this babble.
Eric