While the basic idea of rendering to a virtual DOM is simple, making it work well for large applications require a lot more than a toy implementation as describ

While the basic idea of rendering to a virtual DOM is simple, making it work well for large applications require a lot more than a toy implementation as described in the article. In order to get adopted, React needs to coexist with existing applications/third party libraries that do manual DOM mutations. The life cycle methods are there to deal with this. React implements its own class system that supports mixins and type annotations. The plan is to change the API to use ES6 classes (we're working to improve the standard to support all React use cases). React re-implements its own event system in order to make it fast, memory efficient and abstract away browser differences. Making composable components is not as straightforward as it first seems. There are a lot of edge cases like refs, owner/parent to be handled. Then, as you mentioned, there's the diff algorithm and batching strategies which need to be implemented in a performant and memory efficient way. And provide hooks for the user to be able to give it hints via shouldComponentUpdate.