React, Flux, GraphQL, Hack, HHVM...? All of this and more!
On the server side PHP7 will also have improvements in regards to type handling. André Rømcke gives a good explanation of weak typing in his article discussing typing in PHP 7.0:
So weak type handling is basically a feature for the consumers of interfaces/methods/API’s, it allows the use of a interface to not care so much about type. While the implementation, written by a library developer, gets the exact type it expects, and nothing else. This should thus technically please both sides of the interface(/fence).
Facebook's own adaptation of the PHP language, Hack, also has type annotations: Hack Type Annotations
Learn more about Flow and how to use it your own project: