Lisp programmers have understood the power of the concept of "code as data" for decades. Having a structured representation of your code allows for an untold number of new applications that go far beyond what can be achieved by treating it as a lifeless stream of characters.

Esprima, a parser for javascript pushes your development very far in that direction by allowing you access to an AST (abstract syntax tree) representation of your code, that coupled with the strong conventions and API of React allow for some pretty amazing applications that i'll demonstrate how to implement.