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Add it here! (Please keep the list alphabet * [Montreal, QC - React Native](https://www.meetup.com/fr-FR/React-Native-MTL/) * [Vancouver, BC](https://www.meetup.com/ReactJS-Vancouver-Meetup/) * [Ottawa, ON](https://www.meetup.com/Ottawa-ReactJS-Meetup/) +* [Saskatoon, SK](https://www.meetup.com/saskatoon-react-meetup/) * [Toronto, ON](https://www.meetup.com/Toronto-React-Native/events/) ## Chile {/*chile*/} diff --git a/src/content/learn/describing-the-ui.md b/src/content/learn/describing-the-ui.md index 9d93f397c..2fcb6d733 100644 --- a/src/content/learn/describing-the-ui.md +++ b/src/content/learn/describing-the-ui.md @@ -18,6 +18,7 @@ React — гэта JavaScript бібліятэка для рэндэрынгу * [Як рэндэрыць кампаненты ў залежнасці ад умоў](/learn/conditional-rendering) * [Як рэндэрыць некалькі кампанентаў за раз](/learn/rendering-lists) * [Як пазбягаць памылак, захоўваючы кампанент чыстымі](/learn/keeping-components-pure) +* [Чаму карысна ўяўляць ваш карыстальніцкі інтэрфейс у выглядзе дрэў](/learn/understanding-your-ui-as-a-tree) @@ -523,6 +524,28 @@ export default function TeaSet() { +## Карыстальніцкі інтэрфейс у выглядзе дрэва {/*your-ui-as-a-tree*/} + +React выкарыстоўвае дрэвы для мадэліравання адносін паміж кампанентамі і модулямі. + +Дрэва рэндэрынгу React — гэта адлюстраванне бацькоўскіх і даччыных адносін паміж кампанентамі. + +Прыклад дрэва рэндэрынгу React. + +Кампаненты, якія знаходзяцца ў верхняй частцы дрэва, каля каранёвага кампанента, лічацца кампанентамі верхняга ўзроўню. Кампаненты без даччыных кампанентаў з'яўляюцца ліставымі кампанентамі. Такая класіфікацыя кампанентаў карысная для разумення патоку даных і прадукцыйнасці рэндэрынгу. + +Мадэліраванне адносін паміж модулямі JavaScript — гэта яшчэ адзін карысны спосаб зразумець вашу праграму. Мы называем гэта «дрэвам залежнасці модуляў». + +Прыклад дрэва залежнасцяў модуля. + +Дрэва залежнасцяў часта выкарыстоўваецца інструментамі зборкі для аб'яднання ўсяго адпаведнага JavaScript кода для спампоўвання і адлюстравання кліентам. Вялікі памер пакета пагаршае карыстальніцкі досвед узаемадзеяння з праграмамі напісанымі з дапамогай React. Разуменне дрэва залежнасцяў модуля дапамагае вырашаць такія праблемы. + + + +Азнаёмцеся са старонкай «**[Карыстальніцкі інтэрфейс у выглядзе дрэва](/learn/understanding-your-ui-as-a-tree)**» каб даведацца як ствараць дрэвы рэндэрынгу і дрэва залежнасцяў модуля для праграмы React і як гэтыя ментальныя мадэлі дапамагаюць палепшыць карыстальніцкі досвед і прадукцыйнасць. + + + ## Наступныя крокі {/*whats-next*/} Пачніце са старонкі «[Ваш першы кампанент](/learn/your-first-component)» каб пачаць чытанне главы старонка за старонкай! diff --git a/src/content/learn/preserving-and-resetting-state.md b/src/content/learn/preserving-and-resetting-state.md index 1c9c341fb..709d9e3d3 100644 --- a/src/content/learn/preserving-and-resetting-state.md +++ b/src/content/learn/preserving-and-resetting-state.md @@ -10,33 +10,17 @@ State is isolated between components. React keeps track of which state belongs t -* How React "sees" component structures * When React chooses to preserve or reset the state * How to force React to reset component's state * How keys and types affect whether the state is preserved -## The UI tree {/*the-ui-tree*/} +## State is tied to a position in the render tree {/*state-is-tied-to-a-position-in-the-tree*/} -Browsers use many tree structures to model UI. The [DOM](https://developer.mozilla.org/docs/Web/API/Document_Object_Model/Introduction) represents HTML elements, the [CSSOM](https://developer.mozilla.org/docs/Web/API/CSS_Object_Model) does the same for CSS. There's even an [Accessibility tree](https://developer.mozilla.org/docs/Glossary/Accessibility_tree)! - -React also uses tree structures to manage and model the UI you make. React makes **UI trees** from your JSX. Then React DOM updates the browser DOM elements to match that UI tree. (React Native translates these trees into elements specific to mobile platforms.) - - - - - -From components, React creates a UI tree which React DOM uses to render the DOM - - - - - -## State is tied to a position in the tree {/*state-is-tied-to-a-position-in-the-tree*/} - -When you give a component state, you might think the state "lives" inside the component. But the state is actually held inside React. React associates each piece of state it's holding with the correct component by where that component sits in the UI tree. +React builds [render trees](learn/understanding-your-ui-as-a-tree#the-render-tree) for the component structure in your UI. +When you give a component state, you might think the state "lives" inside the component. But the state is actually held inside React. React associates each piece of state it's holding with the correct component by where that component sits in the render tree. Here, there is only one `` JSX tag, but it's rendered at two different positions: @@ -190,7 +174,7 @@ Updating state -React will keep the state around for as long as you render the same component at the same position. To see this, increment both counters, then remove the second component by unchecking "Render the second counter" checkbox, and then add it back by ticking it again: +React will keep the state around for as long as you render the same component at the same position in the tree. To see this, increment both counters, then remove the second component by unchecking "Render the second counter" checkbox, and then add it back by ticking it again: diff --git a/src/content/learn/understanding-your-ui-as-a-tree.md b/src/content/learn/understanding-your-ui-as-a-tree.md new file mode 100644 index 000000000..2a5a24b85 --- /dev/null +++ b/src/content/learn/understanding-your-ui-as-a-tree.md @@ -0,0 +1,300 @@ +--- +title: Understanding Your UI as a Tree +--- + + + +Your React app is taking shape with many components being nested within each other. How does React keep track of your app's component structure? + +React, and many other UI libraries, model UI as a tree. Thinking of your app as a tree is useful for understanding the relationship between components. This understanding will help you debug future concepts like performance and state management. + + + + + +* How React "sees" component structures +* What a render tree is and what it is useful for +* What a module dependency tree is and what it is useful for + + + +## Your UI as a tree {/*your-ui-as-a-tree*/} + +Trees are a relationship model between items and UI is often represented using tree structures. For example, browsers use tree structures to model HTML ([DOM](https://developer.mozilla.org/docs/Web/API/Document_Object_Model/Introduction)) and CSS ([CSSOM](https://developer.mozilla.org/docs/Web/API/CSS_Object_Model)). Mobile platforms also use trees to represent their view hierarchy. + + + +React creates a UI tree from your components. In this example, the UI tree is then used to render to the DOM. + + +Like browsers and mobile platforms, React also uses tree structures to manage and model the relationship between components in a React app. These trees are useful tools to understand how data flows through a React app and how to optimize rendering and app size. + +## The Render Tree {/*the-render-tree*/} + +A major feature of components is the ability to compose components of other components. As we [nest components](/learn/your-first-component#nesting-and-organizing-components), we have the concept of parent and child components, where each parent component may itself be a child of another component. + +When we render a React app, we can model this relationship in a tree, known as the render tree. + +Here is a React app that renders inspirational quotes. + + + +```js App.js +import FancyText from './FancyText'; +import InspirationGenerator from './InspirationGenerator'; +import Copyright from './Copyright'; + +export default function App() { + return ( + <> + + + + + + ); +} + +``` + +```js FancyText.js +export default function FancyText({title, text}) { + return title + ?

{text}

+ :

{text}

+} +``` + +```js InspirationGenerator.js +import * as React from 'react'; +import quotes from './quotes'; +import FancyText from './FancyText'; + +export default function InspirationGenerator({children}) { + const [index, setIndex] = React.useState(0); + const quote = quotes[index]; + const next = () => setIndex((index + 1) % quotes.length); + + return ( + <> +

Your inspirational quote is:

+ + + {children} + + ); +} +``` + +```js Copyright.js +export default function Copyright({year}) { + return

©️ {year}

; +} +``` + +```js quotes.js +export default [ + "Don’t let yesterday take up too much of today.” — Will Rogers", + "Ambition is putting a ladder against the sky.", + "A joy that's shared is a joy made double.", + ]; +``` + +```css +.fancy { + font-family: 'Georgia'; +} +.title { + color: #007AA3; + text-decoration: underline; +} +.cursive { + font-style: italic; +} +.small { + font-size: 10px; +} +``` + + + + + +React creates a *render tree*, a UI tree, composed of the rendered components. + + + + +From the example app, we can construct the above render tree. + +The tree is composed of nodes, each of which represents a component. `App`, `FancyText`, `Copyright`, to name a few, are all nodes in our tree. + +The root node in a React render tree is the [root component](/learn/importing-and-exporting-components#the-root-component-file) of the app. In this case, the root component is `App` and it is the first component React renders. Each arrow in the tree points from a parent component to a child component. + + + +#### Where are the HTML tags in the render tree? {/*where-are-the-html-elements-in-the-render-tree*/} + +You'll notice in the above render tree, there is no mention of the HTML tags that each component renders. This is because the render tree is only composed of React [components](learn/your-first-component#components-ui-building-blocks). + +React, as a UI framework, is platform agnostic. On react.dev, we showcase examples that render to the web, which uses HTML markup as its UI primitives. But a React app could just as likely render to a mobile or desktop platform, which may use different UI primitives like [UIView](https://developer.apple.com/documentation/uikit/uiview) or [FrameworkElement](https://learn.microsoft.com/en-us/dotnet/api/system.windows.frameworkelement?view=windowsdesktop-7.0). + +These platform UI primitives are not a part of React. React render trees can provide insight to our React app regardless of what platform your app renders to. + + + +A render tree represents a single render pass of a React application. With [conditional rendering](/learn/conditional-rendering), a parent component may render different children depending on the data passed. + +We can update the app to conditionally render either an inspirational quote or color. + + + +```js App.js +import FancyText from './FancyText'; +import InspirationGenerator from './InspirationGenerator'; +import Copyright from './Copyright'; + +export default function App() { + return ( + <> + + + + + + ); +} + +``` + +```js FancyText.js +export default function FancyText({title, text}) { + return title + ?

{text}

+ :

{text}

+} +``` + +```js Color.js +export default function Color({value}) { + return
+} +``` + +```js InspirationGenerator.js +import * as React from 'react'; +import inspirations from './inspirations'; +import FancyText from './FancyText'; +import Color from './Color'; + +export default function InspirationGenerator({children}) { + const [index, setIndex] = React.useState(0); + const inspiration = inspirations[index]; + const next = () => setIndex((index + 1) % inspirations.length); + + return ( + <> +

Your inspirational {inspiration.type} is:

+ {inspiration.type === 'quote' + ? + : } + + + {children} + + ); +} +``` + +```js Copyright.js +export default function Copyright({year}) { + return

©️ {year}

; +} +``` + +```js inspirations.js +export default [ + {type: 'quote', value: "Don’t let yesterday take up too much of today.” — Will Rogers"}, + {type: 'color', value: "#B73636"}, + {type: 'quote', value: "Ambition is putting a ladder against the sky."}, + {type: 'color', value: "#256266"}, + {type: 'quote', value: "A joy that's shared is a joy made double."}, + {type: 'color', value: "#F9F2B4"}, +]; +``` + +```css +.fancy { + font-family: 'Georgia'; +} +.title { + color: #007AA3; + text-decoration: underline; +} +.cursive { + font-style: italic; +} +.small { + font-size: 10px; +} +.colorbox { + height: 100px; + width: 100px; + margin: 8px; +} +``` + + + + +With conditional rendering, across different renders, the render tree may render different components. + + + +In this example, depending on what `inspiration.type` is, we may render `` or ``. The render tree may be different for each render pass. + +Although render trees may differ across render pases, these trees are generally helpful for identifying what the top-level and leaf components are in a React app. Top-level components are the components nearest to the root component and affect the rendering performance of all the components beneath them and often contain the most complexity. Leaf components are near the bottom of the tree and have no child components and are often frequently re-rendered. + +Identifying these categories of components are useful for understanding data flow and performance of your app. + +## The Module Dependency Tree {/*the-module-dependency-tree*/} + +Another relationship in a React app that can be modeled with a tree are an app's module dependencies. As we [break up our components](/learn/importing-and-exporting-components#exporting-and-importing-a-component) and logic into separate files, we create [JS modules](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Modules) where we may export components, functions, or constants. + +Each node in a module dependency tree is a module and each branch represents an `import` statement in that module. + +If we take the previous Inspirations app, we can build a module dependency tree, or dependency tree for short. + + + +The module dependency tree for the Inspirations app. + + + +The root node of the tree is the root module, also known as the entrypoint file. It often is the module that contains the root component. + +Comparing to the render tree of the same app, there are similar structures but some notable differences: + +* The nodes that make-up the tree represent modules, not components. +* Non-component modules, like `inspirations.js`, are also represented in this tree. The render tree only encapsulates components. +* `Copyright.js` appears under `App.js` but in the render tree, `Copyright`, the component, appears as a child of `InspirationGenerator`. This is because `InspirationGenerator` accepts JSX as [children props](/learn/passing-props-to-a-component#passing-jsx-as-children), so it renders `Copyright` as a child component but does not import the module. + +Dependency trees are useful to determine what modules are necessary to run your React app. When building a React app for production, there is typically a build step that will bundle all the necessary JavaScript to ship to the client. The tool responsible for this is called a [bundler](https://developer.mozilla.org/en-US/docs/Learn/Tools_and_testing/Understanding_client-side_tools/Overview#the_modern_tooling_ecosystem), and bundlers will use the dependency tree to determine what modules should be included. + +As your app grows, often the bundle size does too. Large bundle sizes are expensive for a client to download and run. Large bundle sizes can delay the time for your UI to get drawn. Getting a sense of your app's dependency tree may help with debugging these issues. + +[comment]: <> (perhaps we should also deep dive on conditional imports) + + + +* Trees are a common way to represent the relationship between entities. They are often used to model UI. +* Render trees represent the nested relationship between React components across a single render. +* With conditional rendering, the render tree may change across different renders. With different prop values, components may render different children components. +* Render trees help identify what the top-level and leaf components are. Top-level components affect the rendering performance of all components beneath them and leaf components are often re-rendered frequently. Identifying them is useful for understanding and debugging rendering performance. +* Dependency trees represent the module dependencies in a React app. +* Dependency trees are used by build tools to bundle the necessary code to ship an app. +* Dependency trees are useful for debugging large bundle sizes that slow time to paint and expose opportunities for optimizing what code is bundled. + + + +[TODO]: <> (Add challenges) diff --git a/src/content/reference/react-dom/components/common.md b/src/content/reference/react-dom/components/common.md index 8cf1fa29b..78d2713bc 100644 --- a/src/content/reference/react-dom/components/common.md +++ b/src/content/reference/react-dom/components/common.md @@ -694,7 +694,7 @@ An event handler type for the `onWheel` event. ```js
console.log('onScroll')} + onWheel={e => console.log('onWheel')} /> ``` diff --git a/src/content/reference/react-dom/hooks/index.md b/src/content/reference/react-dom/hooks/index.md new file mode 100644 index 000000000..6490dc111 --- /dev/null +++ b/src/content/reference/react-dom/hooks/index.md @@ -0,0 +1,48 @@ +--- +title: "React DOM Hooks" +--- + + + +The `react-dom` package contains Hooks that are only supported for web applications (which run in the browser DOM environment). These Hooks are not supported in non-browser environments like iOS, Android, or Windows applications. If you are looking for Hooks that are supported in web browsers *and other environments* see [the React Hooks page](/reference/react). This page lists all the Hooks in the `react-dom` package. + + + +--- + +## Form Hooks {/*form-hooks*/} + + + +Form Hooks are currently only available in React's canary and experimental channels. Learn more about [React's release channels here](/community/versioning-policy#all-release-channels). + + + +*Forms* let you create interactive controls for submitting information. To manage forms in your components, use one of these Hooks: + +* [`useFormStatus`](/reference/react-dom/hooks/useFormStatus) allows you to make updates to the UI based on the status of the a form. +* `useFormState` allows you to manage state inside a form. + +```js +function Form({ action }) { + async function increment(n) { + return n + 1; + } + const [count, incrementFormAction] = useFormState(increment, 0); + return ( +
+ +
+ ); +} +``` diff --git a/src/content/reference/react-dom/hooks/useFormStatus.md b/src/content/reference/react-dom/hooks/useFormStatus.md new file mode 100644 index 000000000..abaa9b6f2 --- /dev/null +++ b/src/content/reference/react-dom/hooks/useFormStatus.md @@ -0,0 +1,261 @@ +--- +title: useFormStatus +canary: true +--- + + + +The `useFormStatus` Hook is currently only available in React's canary and experimental channels. Learn more about [React's release channels here](/community/versioning-policy#all-release-channels). + + + + + +`useFormStatus` is a Hook that gives you status information of the last form submission. + +```js +const { pending, data, method, action } = useFormStatus(); +``` + + + + + +--- + +## Reference {/*reference*/} + +### `useFormStatus()` {/*use-form-status*/} + +The `useFormStatus` Hook provides status information of the last form submission. + +```js {5},[[1, 6, "status.pending"]] +import { useFormStatus } from "react-dom"; +import action from './actions'; + +function Submit() { + const status = useFormStatus(); + return +} + +export default App() { + return ( +
+ + + ); +} +``` + +To get status information, the `Submit` component must be rendered within a `
`. The Hook returns information like the `pending` property which tells you if the form is actively submitting. + +In the above example, `Submit` uses this information to disable ` + ); +} + +function Form({ action }) { + return ( + + + + ); +} + +export default function App() { + return
; +} +``` + +```js actions.js hidden +export async function submitForm(query) { + await new Promise((res) => setTimeout(res, 1000)); +} +``` + +```json package.json hidden +{ + "dependencies": { + "react": "canary", + "react-dom": "canary", + "react-scripts": "^5.0.0" + }, + "main": "/index.js", + "devDependencies": {} +} +``` + + + + +##### `useFormStatus` will not return status information for a `` rendered in the same component. {/*useformstatus-will-not-return-status-information-for-a-form-rendered-in-the-same-component*/} + +The `useFormStatus` Hook only returns status information for a parent `` and not for any `` rendered in the same component calling the Hook, or child components. + +```js +function Form() { + // 🚩 `pending` will never be true + // useFormStatus does not track the form rendered in this component + const { pending } = useFormStatus(); + return ; +} +``` + +Instead call `useFormStatus` from inside a component that is located inside `
`. + +```js +function Submit() { + // ✅ `pending` will be derived from the form that wraps the Submit component + const { pending } = useFormStatus(); + return ; +} + +function Form() { + // This is the `useFormStatus` tracks + return ( + + + + ); +} +``` + +
+ +### Read the form data being submitted {/*read-form-data-being-submitted*/} + +You can use the `data` property of the status information returned from `useFormStatus` to display what data is being submitted by the user. + +Here, we have a form where users can request a username. We can use `useFormStatus` to display a temporary status message confirming what username they have requested. + + + +```js UsernameForm.js active +import {useState, useMemo, useRef} from 'react'; +import {useFormStatus} from 'react-dom'; + +export default function UsernameForm() { + const {pending, data} = useFormStatus(); + + const [showSubmitted, setShowSubmitted] = useState(false); + const submittedUsername = useRef(null); + const timeoutId = useRef(null); + + useMemo(() => { + if (pending) { + submittedUsername.current = data?.get('username'); + if (timeoutId.current != null) { + clearTimeout(timeoutId.current); + } + + timeoutId.current = setTimeout(() => { + timeoutId.current = null; + setShowSubmitted(false); + }, 2000); + setShowSubmitted(true); + } + }, [pending, data]); + + return ( + <> +
+ + + {showSubmitted ? ( +

Submitted request for username: {submittedUsername.current}

+ ) : null} + + ); +} +``` + +```js App.js +import UsernameForm from './UsernameForm'; +import { submitForm } from "./actions.js"; + +export default function App() { + return ( +
+ + + ); +} +``` + +```js actions.js hidden +export async function submitForm(query) { + await new Promise((res) => setTimeout(res, 1000)); +} +``` + +```json package.json hidden +{ + "dependencies": { + "react": "canary", + "react-dom": "canary", + "react-scripts": "^5.0.0" + }, + "main": "/index.js", + "devDependencies": {} +} +``` +
 + +--- + +## Troubleshooting {/*troubleshooting*/} + +### `status.pending` is never `true` {/*pending-is-never-true*/} + +`useFormStatus` will only return status information for a parent `
`. + +If the component that calls `useFormStatus` is not nested in a ``, `status.pending` will always return `false`. Verify `useFormStatus` is called in a component that is a child of a `` element. + +`useFormStatus` will not track the status of a `` rendered in the same component. See [Pitfall](#useformstatus-will-not-return-status-information-for-a-form-rendered-in-the-same-component) for more details. diff --git a/src/content/reference/react/cache.md b/src/content/reference/react/cache.md index 7f9afdb99..65d95ab76 100644 --- a/src/content/reference/react/cache.md +++ b/src/content/reference/react/cache.md @@ -252,7 +252,7 @@ function Page({id}) { When rendering `Page`, the component calls `getUser` but note that it doesn't use the returned data. This early `getUser` call kicks off the asynchronous database query that occurs while `Page` is doing other computational work and rendering children. -When rendering `Profile`, we call `getUser` again. If the initial `getUser` call has already returned and cached the user data, when when `Profile` asks and waits for this data, it can simply read from the cache without requiring another remote procedure call. If the initial data request hasn't been completed, preloading data in this pattern reduces delay in data-fetching. +When rendering `Profile`, we call `getUser` again. If the initial `getUser` call has already returned and cached the user data, when `Profile` asks and waits for this data, it can simply read from the cache without requiring another remote procedure call. If the initial data request hasn't been completed, preloading data in this pattern reduces delay in data-fetching. diff --git a/src/pages/_document.tsx b/src/pages/_document.tsx index 392fdf88a..d8fb0c621 100644 --- a/src/pages/_document.tsx +++ b/src/pages/_document.tsx @@ -9,6 +9,15 @@ const MyDocument = () => { return ( +