Context Hook

[00:00] All right. So what's going on is because we're not wrapping this in our provider, we're not doing any of the provider stuff in here. In fact, this is an unused variable. So all of the stuff that's responsible for listening to pop state and for setting search

[00:15] params like that set search params function, all of that stuff is not being used. And so, while we may be all accessing the same type of thing and able to set the global search params, that works out just fine. And we're able to get the initial URL search params. So if I were to

[00:35] say query dog, like that's filtering fine. But when we try to update, it's just updating the URL and not actually able to feed into our search params that we're using for our UI. So I find

[00:52] this actually quite a lot that my context providers do not make sense to have a default value. And instead, I say no for my default value. And then down here in my context consumer,

[01:10] I find that it's really annoying to have to do null checks for all of these uses of the use search params, because now it could be search params tuple or null. And that absolutely can be null because we're not rendering our provider yet. And so my use search params hook here is

[01:28] going to check if there's no context. And if there's not, then we're going to let people know, hey, use search params must be used within a search params provider. And so now we're blowing up but at least we get a nice error message explaining exactly what I just said. So what

[01:47] we need to do now is add the search params provider and close that off. And now we are within a search params provider. And as I type, it is updating again, we fixed it. Good job

[02:01] caterpillar. There we go. And uncheck that. Oh, it's so cool. All this good stuff. So most of the time, not always, for sure, there are situations where having a default makes sense. But most of the time, I find myself setting this to null, and then having the context do the null check for me

[02:20] so I don't have to do it all over my code base. So there you go. That is handling the default in a more expert way.

[00:00] So Kelly was looking around the app, and she noticed, hey, we've got a default value for our context, so we probably don't need to render the search params context at all. Like, when we say use, we're going to just get this, and this looks good. So Kelly removed our context provider, and now the app is busted.

[00:19] We are updating the URL, but we're not filtering properly. And we're not actually, look, I'm typing in here. Nothing's happening. We're in trouble. Something is not connecting quite right. I want you to play around with it and try and figure out if you understand why that's not working, and then let's remove this default value,

[00:37] because it is totally borking our user experience. And yeah, then we'll see you when you're done.

Advanced React APIs covers many of the React APIs that you might not see on a day-to-day basis but you will need these in your toolbelt for certain scenarios that pop up.

We'll take a tour of several advanced hooks and React API, their use-cases, and when to use them. 

These will include:

- useReducer
- use
- createContext
- useLayoutEffect
- useImperativeHandle
- useSyncExternalStore
- flushSync
- createPortal


## Complex State Management

First we'll dive into the deep-end of state management with `useReducer`. This hook comes in really handy when you feel the logic in your components is a sprawling mess and you'd like to consolidate that into a single place with a nice API to interact with. 

We'll get into some state optimizations as well as how to make your logic easily sharable throughout your application with custom hooks.

## Context

While context is often times something you will leave up to library authors, there are some cases where you want to expose values you need throughout your application. We'll build a context provider that will expose search params to our components on a blog search page with `use` (previously `useContext`) and `createContext`.

You'll also refactor this code to expose the context you create in a custom hook that will give us nice error handling when context isn't set up correctly.

## Portals

React gives us `createPortal` to render UI outside of the DOM tree structure that a component might sit in. This is useful for UI elements like modals or tooltips. We'll explore how to attach a tooltip to the `document.body` to ensure it's positioned where it needs to go.

## Layout Computations

If the logic that you are working with in a `useEffect` affects the how the UI looks, especially on first render, you'll want to `useLayoutEffect`. You'll work through an exercise where the client makes calculations on where to place a tooltip before rendering and see the difference when this is in a `useLayoutEffect`.

## Imperative Handles

`useImperativeHandle` is an escape hatch in React that lets you imperatively tell React what to do. This hook is typically paired with a ref (from `useRef`) where we want to expose imperative methods to developers who pass a ref prop to our components.

## Focus Management

`flushSync` is technically a 'de-optimization' because it forces React to re-render whenever you call it. This means you need to be very careful and know what you're doing when you use it.

The primary use-case for this API is focus management. When you have conditional UI that gets rendered based on various state conditions, you can `flushSync` to ensure elements are in the DOM to properly focus.

## Sync Exernal Store

There are some cases where we want to synce our React code with the external world and display different UI based on the state of the external world. This is where `useSyncExternalStore` is useful and lets you subscribe to external stores. We'll also touch on server rendering as this hook supports that use-case.

Learn the hooks and API that React has to offer for complex state management, sharing context throughout your app, focus management and more.

Advanced React APIs

Kent C. Dodds

React Fundamentals

React Hooks

React Suspense

Advanced React Patterns

React Performance

React Server Components

Epic React Pro

Advanced React APIs Intro

Intro to Advanced State Management

New State

Previous State

State Object

Action Function

Traditional Reducer

Real World

Dad Joke Break Advanced State Management

Advanced State Management

Intro to State Optimization

Optimize state updates

Dad Joke Break State Optimization

State Optimization

Intro to Custom Hooks

Hook Function

useCallback

Dad Joke Break Custom Hooks 

Custom Hooks

Intro to Shared Context 

Context Provider

Dad Joke Break Shared Context 

Shared Context

Intro to Portals

createPortal

Dad Joke Break Portals 

Portals

Intro to Layout Computation 

useLayoutEffect

Dad Joke Break Layout Computation 

Layout Computation

Intro to Imperative Handles

useImperativeHandle

Dad Joke Break Imperative Handles 

Imperative Handles 

Intro to Focus Management 

flushSync

Dad Joke Break Focus Management 

Focus Management

Intro to Sync External State 

useSyncExternalStore

Make Store Utility

Handling Server Rendering

Dad Joke Break Sync External State

Sync External State

Outro to Advanced React APIs

Advanced React APIs

Advanced React APIs

Transcript

Context Hook

Transcript