There are multiple Frameworks available in the current market like Knockout JS, Ember, Backbone, Angular JS and many more. And the trend of traditional JavaScript programming is changing and moving towards MV* frameworks.
Now IT field demands knowledge of at least one of the knowledge of JS frameworks. Companies are looking for the people with having knowledge of these popular frameworks apart from HTML5, CSS3, jQuery knowledge.

Hence, pick any of your favorite frameworks and start practicing. It would help us in our career for sure. :)