we will talking today about javascript frameworks
first : what we mean by javascript framework ??
“A software framework, in computer programming, is an abstraction in which common code providing generic functionality can be selectively overridden or specialized by user code providing specific functionality.”
from wikipedia
so we can say that javascript framework is abstracting to tranditional javascript codes so you can do amazing things with javascript just with a few lines of code
you can control DOM ,doing amazing animation , ajax and alot of cool things that helps when you develop a website
now ,we  knows what it means but there is alot of frameworks what is the best
we will go in a short tour with the best 10 javascript frameworks

1- jquery:-

the best framework ever for javascript , specially with the new realese 1.3 the jquery become lighter , faster , more powerful
you can control DOM easly with the DOM engine using CSS3
website :-  jquery.com
license : MIT & GPL

2- prototype:-

the fastest framework it really very fast an also contain a good DOM engine but not powerful as  jquery.
note: i tried very hard to make prototype works side by side but i failed so if you have any ideas please suggest:)
website:- www.prototypejs.org
license : GPL

3- mootools:-

its a really a nice one , honestly i didn’t work with it but many developers prefer it , i saw many demos but i didnt test its DOM engine ( if you test it please feed back me)
website:- mootools.net
license : GPL

4- google web toolkit:-

big big big so big one , it have many features i cant even imagine how google developers code it , google
in short:- it perfectly for large projects , it have many features you cant find in any other framework
website :- code.google.com/webtoolkit
license:- Apache License

5- Ext Js:-

big framework too , but so slow in compare with other frameworks , so big and so complicated too.
website :- extjs.com
license:- commercial version  1.3

6- DOJO :-

new framework i didnt test it , but many developers beign to work with , so easy and powerful , and may be it face jquery & prototype & mootools one day
website :- www.dojotoolkit.org
license :- BSD & AFL

7- script.aculo.us :-

poor framework , based on protoype ,  it have small features and i dont recommended it
website :- script.aculo.us
license : GPL

8- YUI:-

big framework coded by yahoo , but so big so complex as ext js
website:- developer.yahoo.com/yui
license:- BSD License

9- midori:-

small but good framework for small projects
website :- www.midorijs.com
license :- MIT License

10-MochiKit:-

small but good framework for small projects, highly documented as they said
website:- mochikit.com
license :- MIT & AFL

that is all i have for now , if you have any other javascript frameworks do you want to add to this list , just comment
references:- frameworks websites , wikipedia , and   google