What’s new with React? New lifecycle methods, context API, hooks, and lots more. While the fundamental principles of React have stayed the same, the way we write React apps has changed with each new release.  

If you learned React a while back, it’s possible that you haven’t been up to date with every new feature/release. It’s also possible to get lost in all the new features. Where exactly do you start? How important are they for your day to day use?

This course is your one-stop reference to most important React updates since V16 was released. We’ll walk through all the major features of modern React so you can stay in sync with the most recent changes while learning to write better software.

Reintroducing React: V16 and Beyond

## The `componentDidUpdate` Lifecycle Method

The `getSnapshotBeforeUpdate` lifecycle method doesn't work on its own. It is meant to be used in conjunction with the `componentDidUpdate` lifecycle method.

Whatever value is returned from the `getSnapshotBeforeUpdate` lifecycle method is passed as the third argument to the `componentDidUpdate` method.
Let’s call the returned value from `getSnapshotBeforeUpdate`, *snapshot*. Here's what we get:



# The `componentDidUpdate` Lifecycle Method

The `getSnapshotBeforeUpdate` lifecycle method doesn't work on its own. It is meant to be used in conjunction with the `componentDidUpdate` lifecycle method.

Whatever value is returned from the `getSnapshotBeforeUpdate` lifecycle method is passed as the third argument to the `componentDidUpdate` method.
Let’s call the returned value from `getSnapshotBeforeUpdate`, *snapshot*. Here's what we get:



This lesson is an extension of the previous lesson. We'll discuss getSnapshotBeforeUpdate components and the chat panel in more detail.

Introduction

Lifecycle

Context API

ContextType

React.memo

The Profiler

Lazy Loading

Hooks

Conclusion

Method 2: getSnapshotBeforeUpdate Extension in Detail

The `componentDidUpdate` Lifecycle Method