This is a very general introduction to MV* Javascript frameworks. This card won't tell you anything new if you are already familiar with the products mentioned in the title.
As web applications move farther into the client, Javascript frameworks have sprung up that operate on a higher level of abstraction than DOM manipulation frameworks like jQuery and Prototype. Such high-level frameworks typically offer support for client-side view rendering, routing, data bindings, etc. This is useful, and when you write a moderately complex Javascript application with jQuery alone, you'll often either implement these features yourself, or end up with a mess of events and callbacks.
For a long time there has been no clear winner between the various high-level Javascript frameworks (sometimes called MV* frameworks). In 2011 Backbone.js Show archive.org snapshot gained a lot of popularity. It has recently been challenged by Yehudo Katz' Ember.js Show archive.org snapshot . Both frameworks are leightweight, but they have very different philosophies and tastes in design. I recommend reading Backbone and Ember Show archive.org snapshot by Boris Smus for a very reflected comparison between the two.
Even though Ember and Backbone are receiving a lot of attention currently, there are other frameworks with interesting approaches such as Knockout Show archive.org snapshot . You will probably need to take them for a ride in a sample project in order to decide which style fits you best.
A nice way to compare different MV* frameworks is TodoMVC Show archive.org snapshot , which shows different implementations of the same sample project in different MV* frameworks. If you are looking for an article that compares frameworks, I recommend Rich Javascript applications: The seven frameworks Show archive.org snapshot .