javascript is known to every browser.
You do not install it - it is one of the languages they know.
But javascript can be turned off.
Or You can have a really old browser.
But I do not know which browser You have.
If You install a new browser You would have new javascript:
e. g. with
Firefox 1.5.0.9 javascript is on by default.
(with version 2 AFAIK also)
Opera 9.02 javascript is on by default.
Their download about 5 mb. links for them and other browsers via:
http://www.alternativebrowseralliance.com/browsers.html#cross
The routine: download, double-click installer, tell firewall that the new browser must be allowed to pass. Finished. Start surfing.
btw. there are aninmations and other contend done with another programming language called Java. That must be installed like a Flash Player. This will get You the newest version.
https://sdlc2a.sun.com/ECom/EComActionServlet;jsessionid=4F70731886BBC4C064859DCADCC3260C
Activate for Your browser like either IE or all others.
This Home Page features Java animations called lake applets: http://home.htp-tel.de/sterntaler/index1.html