New React 16 features August 8, 2018

Purpose

To gain an understanding of new features available in React V16 and look for opportunities where these might be applied to work on the project.

componentWill(Mount|ReceiveProps|Update) are being deprecated and will be removed in React 17. E-Verify UI makes use of all three.
It's good that they're being deprecated because our implementation is an anti-pattern. componentWillMount fires before the render, but is asynchronous. Rather than racing and hoping that componentWillMount will finish before you need it, the initial render should include good default state that permits a complete render, and then componentDidMount can get the updates to state and trigger a new render.
SAVE Mod utilizes componentWillReceiveProps in one place and can refactor that use case for the new getDerivedStateFromProps which modifies state before rendering using the newly received set of props. https://reactjs.org/docs/react-component.html#static-getderivedstatefromprops

The biggest thing with returning fragments rather than DOM elements is that you can think of React components by their function and not just by what makes sense as a DOM element
For example, if you don't need to do DOM manipulation on a piece of functionality, you can still create a React component by returning a fragment
This can simplify/clean up your DOM tree by eliminating unnecessary nodes created for the sake of being able to render a component

React 16.3 introduced the first official Context API for React
It allows for data to be passed around a React application without have to "drill down" (pass via props multiple levels down through other components that don't need it)
Instead, related state can be kept in one place and shared with other components with Provider and Consumer components
Similar to the Redux pattern (and designed by the same person, Dan Abramov) but allows for multiple stores of state (instead of the singular store in Redux)
For updating state, functions can be passed as values via Context as well