In addition to the frameworks listed above, there are a number of Javascript frameworks that are primarily intended to streamline Javascript development by dealing with inconsistency issues in the browser, and providing a more user friendly API.
jQuery
jQuery is a cross-browser library that focuses on the interaction between JavaScript and HTML. It is currently used in as many as 20% of the 10,000 biggest websites in the world, and is largely considered to be the most popular Javascript library around.
MooTools
MooTools is an open source object-oriented Javascript based framework that allows cross-browser compatibility in an elegant and flexible package. MooTools offers the benefits of a comprehensive and easy to use application programming interface.
Prototype
Prototype is a Javascript framework that sangram lad uk offers a number of utilities including an Ajax framework. Although it is usually distributed as a standalone application, it is also commonly used in conjunction with Ruby on Rails and various other frameworks.