Learn Recoil, Redwoodjs and Scikit-learn

React is one of the web’s most popular frameworks for building JavaScript applications. 

If you know what you’re doing, React can drastically simplify how you build, use, and maintain code.

Whether you’re a React newbie or you’re ready for advanced techniques, you can level-up with egghead. Explore our in-depth courses, lessons, and community resources to build more powerful applications and crack open your career.

react

Recoil offers several hooks to use for consuming state in React, and this lesson looks at how to choose which hook to use, and what happens when you don't use the right hook (hint: **extra renders**).

The three basic RecoilJS hooks are:

1. `useRecoilState`, which is great for reading and writing state,
2. `useRecoilValue`, ideal for reading state, and
3. `useSetRecoilState`, the primary candidate when you just need to write state.

Choose the Right Hook for Your Recoil State

When consuming asynchronous selectors in Recoil, you're going to need to tell React what to render while the API is fetching its data. 

One way to solve this issue is by setting a fallback value using React `Suspense`. But there's another option that gives you fine-grained control, and that's by preventing the selectors from returning a promise in the first place.

In this lesson we're going to have our selectors return Recoil's `Loadable` object, which always contains the current selector value (`contents`) and what state the selector is in (`state`). By consuming this with the `useRecoilValueLoadable` hook rather than the regular `useRecoilValue` hook, we can manually define whatever we want React to render in each of the 3 states: `hasError`, `hasValue`, and `loading`.

Handle Recoil Asynchronous Selectors using Loadables in React

Selectors are great for automatically triggering API calls with Recoil because they are automatically run as soon as any dependencies are updated, and because selectors are shared across your application.

Be aware that Recoil will cache your selector values, so asynchronous selectors are best utilized when the data is not meant to change throughout the life-cycle of an application. Fetching a user's avatar would be a good use case.

When writing asynchronous selectors, one thing to keep in mind is that React must always know what to render - even while your data is being fetched. One solution for this is to use Suspense, a React component that allows you to supply a fallback value to render until your data returns. In this lesson, we'll look at how to call APIs inside selectors and handle situations where selectors return promises.

Use Recoil Selectors to Make API Calls in React

In this lesson, we're going to learn how to create Recoil selectors that accept arguments. These are made possible using the `selectorFamily` utility function.

We'll start with an existing application that uses a regular `selector` to display a sorted array of Todo items, and then we'll refactor it so that we're able to supply the sort type (`ascending` or `descending`) in the React component itself.

For more information on `selectorFamily`, have a look at the official RecoilJS docs: https://recoiljs.org/docs/api-reference/utils/selectorFamily


Use selectorFamily to take arguments in your Recoil selectors

Learn how to set state in Recoil using the `useRecoilState` hook. 

Sound familiar? It should, because it works very similarly to React's built-in `useState` hook (the functional component equivalent of `setState`).

In this lesson, we'll practice removing and adding items from an array that we keep in state using a Recoil atom. We'll create new immutable functions, and then call our setter functions in order to update the state.

Update Recoil State in React using useRecoilState

In this lesson, we're going to show how RecoilJS selectors are used to display computed data in React. While atoms are the go-to state objects in Recoil, selectors are the ideal choice when data can be computed based on existing state - like displaying the price of a restaurant order. And your selector output always remains up to date - just subscribe to it using one of the RecoilJS hooks.

Display Computed Data Using Recoil Selectors in React

Recoil is a new (experimental!) library from facebook that can handle complex shared data across a large react app.

In this collection, we'll create a simple game with React using Recoil, to explore how you can share and update state across an app. 

Recoil is similar to (but different than) Context, Redux, or other shared state libraries (like MobX), but is designed to handle large (and variable) numbers of state that can update without re-rendering your entire app's component tree.

A state management library for React.

Recoil works and thinks like React. Add some to your app and get fast and flexible shared state.

recoil

Getting Started with Recoil in React

[Recoil](https://recoiljs.org/) is a brand new state management library for React, developed by Facebook.

Recoil works and thinks like React. Add some to your app and get fast and flexible shared state.

This quick collection will get you up and running with Recoil, you're going to learn how to:

* add Recoil to your React project
* create a Recoil atom and use it to store a piece of state
* use `useRecoilState` hook to update an atom
* use `useRecoilValue` to access value stored in an atom in a read-only fashion
* use 🔥`selectors`🔥 in order to calculate derived data based on state stored within atoms (this is *really* powerful!) 

Sync State Across Components with Recoil in React

Recoil allows us to use atoms in order to store pieces of state. More often than not in our apps we need to use data that derives from our application state (for instance to multiply height and width stored within a state to calculate area of an element).

Luckily Recoil provides us with a powerful tool to automatically re-calculate derived state value whenever an piece of state changes - selectors.

A [selector](https://recoiljs.org/docs/introduction/core-concepts#selectors) is a pure function that accepts atoms or other selectors as input. When these upstream atoms or selectors are updated, the selector function will be re-evaluated.

In this quick lesson we're going to learn how to use a selector in order to automatically calculate a square of a number whenever a value stored within an atom is going to change

Use Selectors to Calculate Derived Data Based on State Stored within a Recoil Atom

Not every component is going to modify a 'global' state stored in a Recoil atom - in some cases a component just needs to be able to read the value.

In this quick lesson we're going to learn how to use a `useRecoilValue` hook to ensure that a component will be able to read a number stored in a Recoil atom in a read-only fashion. 

Use useRecoilValue Hook to Read a Value From a Recoil Atom

[Recoil](https://twitter.com/recoiljs/status/1260965007954591744) is a brand new state management library for React developed by Facebook.

In this quick lesson we're going to learn how to add it to a React app and how to use a Recoil atom in order to share state between two React components using `useRecoilState` hook

 

Use a Recoil Atom to Share State Between Two React Components

In this free collection on Facebook's new state management library, we'll get started using Recoil in our React applications and then delve into various common use cases that we may encounter in the field.

We'll start with the basics of state management in Recoil: the Atoms and Selectors. Then we'll dive further into the Selector API, an important part of the library. Along the way we'll learn different strategies for handling synchronous and asynchronous Selectors.

Manage React State with Recoil

When we import assets in React components outside of the `public` folder that Nitro reads for assets by default when running the development server we need to tell Nitro how to find them with the `devProxy` configuration option.

```typescript
export default defineNitroConfig({
  renderer: './renderer.ts',
  devProxy: {
    '/app/assets': 'http://localhost:5173/app/assets'
  }
})
```

This is ultimately inadequate in scenarios where you want to import assets arbitrarily and have them "just work" but works in a pinch.



Use devProxy in Nitro Config to Serve Static Imported Assets in Dev Mode via Vite

Learn how to use devProxy in Nitro Config with Vite to serve static assets in React components in dev mode.

Start with a basic Vite React TypeScript app and enhance it for production use by integrating Nitro as the server. 

This requires a custom Vite plugin for nitro as well as a custom renderer and manually creating Nitro config.

The other way to approach this would be to add Vite to a Nitro app instead. Same basic result.

The [Nitro config reference](https://nitro.unjs.io/config) is a great read of you'd like to explore more options.


Configure a Vite React TypeScript Application on a Basic Nitro Server

Configure a Vite React TypeScript app by integrating Nitro for production, using custom plugins, renderers, and configs.

Quick Get Started style introduction to Vite using `pnpm create vite` with the React TypeScript template.

See [more in the official docs](https://vite.dev/guide/).

Create a Vite App with the React TypeScript Preset

Quick guide to start a Vite app using React TypeScript template with pnpm.

Over the years, your application have grown huge. Sometimes, really HUGE.

Many developers have contributed to the codebase. One day they pushed one coding style, a different one another day. Sometimes even different patterns and solutions for similar problems.

You want to keep your codebase consistent. In the Angular ecosystem, there were well established patterns for doing things the right way ™️. But the old solutions are being challenged by signal-based approach.

Eventually, you ask yourself the key question: **Should you integrate with the NEW solutions or stick to the battle-tested ones, but already considered LEGACY**?

That's a very good question indeed. Don't rush with architectural decisions 🤓.

## 👉 First, think of what problems you want to solve by introducing the change.

Do you have 1k LoC Angular components? Maybe even 2k? Do you and your team enjoy working with these? 😏

Where does the **domain logic and state management code** belong to - do you have a clear guidance on which code should be put where? Have you spot that different devs implement similar features in totally different ways?

Do you keep on asking the same questions over and over again: **whether this certain piece of code** should be **imperative** (plain old object properties and variables) or **reactive** (streams)? It'd be nice to keep all thinga reactive, but more often than not, it introduces complexity.

## 👉 Second, think of long-term consequences.

You are going to have more than one way to **manage the state**. But is that really an issue? If your codebase is modular, separate modules should not depend on each other in any way. Inner abstractions of one should be invisible to the other, etc.

You are going to introduce a **new tool**. On one hand, you need to learn it, and so does your team. But on the other hand, it's a breathe of fresh air. And it's useful to question the way you've been doing things so far. Maybe there's a more effective way?

You are going to embrace signal-based APIs. And that means taking taking advantage of Zoneless Angular. This means using all modern Angular APIs. And you know that signals are the future. Why would you want to stick to the **less performant, less type-safe, less flexible and, objectively, less effective solutions**?

## 👉 Finally, plan your INCREMENTAL integration.

INCREMENTAL is the absolute keyword here. You don't want to tell your PM you need to stop delivering features because of a refactor.

Actually, there's no need for a "refactor". Just pick the first new feature to be implemented. Or pick the one that needs to be extended.

NGRX Signal Store allows you to create both very simple & small stores, as well as bigger ones. **Composition** is the key here.

**Start simple**.

Create a `withState` section with the signals that hold the state. That's already reactive. And relatively simple.

```ts
const initialState: CartState = {
  items: ...,
  rebate: ...,
}

export const CartStore = signalStore(
  withState(initialState)
);
```

Create a `withMethods` section to provide ways to change the state:

```ts
export const CartStore = signalStore(
  ...
  withMethods((store) => ({
    addItem(item: ShoppingItem): void {
      patchState(store, (state) => ({ items: [ ...state.items, item ] }));
    },
    ...
);
```

Create a `withComputed` section to provide all derived computations:

```ts
export const CartStore = signalStore(
  ...
  withComputed(({ items }) => ({
    totalPrice: computed(() => items().reduce(...))
    ...
);
```

**Start simple**.

Now you can (literally) **`inject` this code into your existing solution**. All you need is to inject your brand new NGRX Signal Store implementation into a component, or a service:

```ts
@Injectable()
class ExistingBigService {
  cartStore = inject(CartStore)
  //...  
}
```

and that's it! What's beatiful is that NGRX Signal Store should remain an implementation details (of a component, service, etc). It **shouldn't leak outside to the entire application unintentionally**. Small NGRX Signal Stores help us to **keep logic more modular**.

Don't hesitate - give NGRX Signal Store a try! Start with the [_**Scalable Signals Angular Architecture with NGRX Signal Store**_](https://egghead.io/courses/scalable-signals-angular-architecture-with-ngrx-signal-store-a33abd39) course now!

Integrating NGRX Signal Store with an existing Angular application


Integrate NGRX Signal Store into your Angular app incrementally for modular, reactive state management. Improve consistency and performance with modern APIs.

In React 19, managing script tags efficiently within components can lead to performance enhancements and simpler code structures.

Originally, using script tags directly in a React component involved complex setups, like using `useEffect` to dynamically add JavaScript code. For instance, a component might dynamically inject script tags to load external widgets. This approach, while functional, resulted in multiple script tags and duplicate iframe elements. This duplication not only cluttered the output but also negatively impacted performance by loading scripts multiple times.

The workaround for this would be to manually hoist any common scripts and maybe load them when they weren't needed by any components.

With React 19 we now have a more effective method. This involves directly placing the script tag within the React component's return statement. This approach ensures that React handles the script loading, avoiding the duplication of script tags.

By implementing the script tags this way, the loading initiator becomes React DOM, which efficiently manages script loading and deduplication. This setup prevents multiple requests for the same script when the component is rendered multiple times, enhancing the overall application performance.

Furthermore, directly embedding the script tag simplifies the code, making the component cleaner and more maintainable.

Efficiently Render Script Tags in React 19 Components

Learn how to efficiently render script tags in React 19 components to improve performance by avoiding duplicate script loads and simplifying your code.

Let's learn how to dynamically manage title tags in React 19 applications. Rendering `<title>` dynamically is simple enough, however, a challenge arises when multiple title tags are present in the document, which can lead to issues with screen readers and search engine optimization (SEO). The solution presented involves ensuring that only one title tag is rendered at a time by using conditional rendering.

Also we need to make sure to have a single string within the title tag using a template literal, ensuring our HTML remains valid and optimized.


Deduplicate Title tags with React 19

Learn to manage multiple title tags in React 19 dynamically. Ensure accessibility and SEO by preventing duplicate title tags with clear examples.

In React 19, we can easily add a title tag like "Starship Deets" which then appears in the head section of the HTML even when we render it inside our components. This method also applies to meta tags such as character set and viewport settings, which are also lifted to the head section automatically.

This is an awesome feature because it maintains the same composition style we are familiar with in React components. It simplifies the handling of HTML head elements without needing extra setups like `useEffect` for accessing the head section. Even in situations where our components are rendering within a body element, like within a div, we can manage our head content directly within our components. React takes care of hoisting these elements where they need to go.


Hoist Title and Meta tags in React 19

Hoisting title and meta tags directly in React 19 components allows for simpler composition, similar to other React elements. Manage meta and title tags.

<PodcastLinks />

Dax Raad, known for his strong opinions on Twitter, sat down for a chat about web dev, career moves, and building cool stuff. He's not afraid to throw some heat at popular tools like [Next.js](https://nextjs.org/), though he still helps people use it. Dax is particularly excited about local-first development, which he thinks isn't getting enough attention. He argues that sometimes the best web dev move is to step away from web dev entirely and explore other areas of programming.

When it comes to career growth, Dax encourages developers to think beyond the "web dev" label and see themselves as programmers capable of tackling any challenge. He advocates for trying out weird stuff and learning unusual languages, as these experiences can lead to unexpected opportunities. Taking smart risks in your career can open doors to awesome possibilities.

In the business world, Dax is a fan of making "asymmetric bets" - moves with low downside but huge potential upside. He applies this philosophy to his work on [SST](https://sst.dev/), reasoning that even if it fails, he'll walk away with valuable experience. He also emphasizes the importance of resisting quick payouts in favor of potentially bigger wins down the road.

Looking to the future of tech, Dax is betting on local-first development. He sees potential in getting in early on emerging technologies like [Solid.js](https://www.solidjs.com/). Building in public and making connections in new tech communities can pay off in unexpected ways.

Dax also challenges the notion of constant hyper-productivity in tech. He suggests balancing focused work with time for exploration and learning. Sometimes, he points out, what seems like a "dumb" choice (like learning a niche language) can turn out to be a smart career move in the long run.

## Good Stuff Mentioned

- [Next.js](https://nextjs.org/)
- [Vercel](https://vercel.com/)
- [SST](https://sst.dev/)
- [Elixir](https://elixir-lang.org/)
- [Solid.js](https://www.solidjs.com/)
- [RepliCache](https://replicache.dev/)
- [Linear](https://linear.app/)
- [Remix](https://remix.run/)
- [Shopify](https://www.shopify.com/)
- [React](https://react.dev/)

Developer Career Growth and Asymmetric Bets with Dax Raad

<PodcastLinks />

Dev and Joel discuss React Miami conference, praising its fun atmosphere and location. They chat about React Server Components, with Dev sharing his experience building a mini framework. They talk about Vinxi, Nitro, and the unjs ecosystem as tools for creating custom frameworks. The conversation touches on Vue's popularity outside web dev circles and non-web dev conferences. They discuss the benefits of TypeScript and strongly-typed APIs. Dev mentions his upcoming talk on durable objects at [a conference in Dallas](https://x.com/DThompsonDev/status/1829674506237194456). They end by discussing WebSockets, PartyKit, and platform-specific frameworks.

## What's Good?

- [React Miami Conference](https://www.reactmiami.com/) 
- [Brenley Dueck's blog post on Simple RSC with Vinxi:](https://www.brenelz.com/posts/simple-rsc-with-vinxi/)
- [Vinxi](https://github.com/nksaraf/vinxi)
- [Nitro](https://nitro.unjs.io/guide/configuration)
- [unjs ecosystem](https://unjs.io/)
- [Solid Start](https://start.solidjs.com/)
- [TanStack Router](https://tanstack.com/router/latest) 
- [PartyKit](https://github.com/partykit/partykit) 
- [Durable Objects (Cloudflare)](https://developers.cloudflare.com/durable-objects/)
- [Flightcontrol](https://www.flightcontrol.dev/) 
- [SST](https://sst.dev/)
- [OpenNext](https://open-next.js.org/)

Nitro, Vinxi, and RSCs - What's Good with Dev Agrawal

**Note:** This course is being actively developed and more lessons will be added in the future.

Cursor is an AI-enhnaced code editor that allows you to call upon the robots to refactor or stub out functions for you with natural language. 

In this course, John will show you workflows that will save you time and effort by utilizing the features such as its mult-line editing and context.

In particular, by giving Cursor's AI the proper context, whether that's lines of code or multiple files, you'll get better output when trying to extend or refactor logic that's present.


Bite-size video tutorials for badass web developers.

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