A JavaScript library for building user interfaces | React

Just the UI Lots of people use React as the V in MVC. Since React makes no assumptions about the rest of your technology stack, it’s easy to try it out on a small feature in an existing project. Virtual DOM React abstracts away the DOM from you, giving a simpler programming model and better performance. React can also render on the server using Node, and it can power native apps using React Native. Data flow React implements one-way reactive data flow which reduces boilerplate and is easier to reason about than traditional data binding.
https://facebook.github.io/react/

Flux | Application Architecture for Building User Interfaces

Flux is the application architecture that Facebook uses for building client-side web applications. It complements React’s composable view components by utilizing a unidirectional data flow. It’s more of a pattern rather than a formal framework, and you can start using Flux immediately without a lot of new code.
https://facebook.github.io/flux/