├── .gitattributes ├── .gitignore ├── CODE_OF_CONDUCT.md ├── CONTRIBUTING.md ├── LICENSE ├── README.md ├── languageFix.jsx ├── logo.png ├── snippet-template.md └── snippets ├── accordion.md ├── alert.md ├── auto-link.md ├── callto.md ├── carousel.md ├── collapse.md ├── controlled-input.md ├── count-down.md ├── data-list.md ├── data-table.md ├── file-drop.md ├── lazy-load-image.md ├── limited-textarea.md ├── limited-word-textarea.md ├── loader.md ├── mailto.md ├── mapped-table.md ├── modal.md ├── multiselect-checkbox.md ├── password-revealer.md ├── ripple-button.md ├── select.md ├── slider.md ├── star-rating.md ├── tabs.md ├── tag-input.md ├── text-area.md ├── toggle.md ├── tooltip.md ├── tree-view.md ├── uncontrolled-input.md ├── use-async.md ├── use-body-scroll-lock.md ├── use-click-inside.md ├── use-click-outside.md ├── use-component-did-mount.md ├── use-component-did-update.md ├── use-component-will-unmount.md ├── use-copy-to-clipboard.md ├── use-debounce.md ├── use-default.md ├── use-delayed-state.md ├── use-effect-once.md ├── use-error.md ├── use-event-listener.md ├── use-fetch.md ├── use-form.md ├── use-get-set.md ├── use-hash.md ├── use-hover.md ├── use-intersection-observer.md ├── use-interval.md ├── use-isomporphic-effect.md ├── use-key-press.md ├── use-local-storage.md ├── use-map.md ├── use-media-query.md ├── use-merge-state.md ├── use-mutation-observer.md ├── use-navigator-on-line.md ├── use-on-global-event.md ├── use-on-window-resize.md ├── use-on-window-scroll.md ├── use-persisted-state.md ├── use-portal.md ├── use-previous.md ├── use-request-animation-frame.md ├── use-script.md ├── use-search-param.md ├── use-session-storage.md ├── use-set.md ├── use-ssr.md ├── use-timeout.md ├── use-title.md ├── use-toggler.md ├── use-unload.md ├── use-update.md └── use-window-size.md /.gitattributes: -------------------------------------------------------------------------------- 1 | src/docs/* linguist-documentation 2 | scripts/* linguist-documentation 3 | gatsby-browser.js linguist-documentation 4 | gatsby-config.js linguist-documentation 5 | gatsby-node.js linguist-documentation 6 | gatsby-ssr.js linguist-documentation 7 | .travis/* linguist-documentation 8 | -------------------------------------------------------------------------------- /.gitignore: -------------------------------------------------------------------------------- 1 | # Logs 2 | logs 3 | *.log 4 | npm-debug.log* 5 | yarn-debug.log* 6 | yarn-error.log* 7 | 8 | # Runtime data 9 | pids 10 | *.pid 11 | *.seed 12 | *.pid.lock 13 | 14 | # Directory for instrumented libs generated by jscoverage/JSCover 15 | lib-cov 16 | 17 | # Coverage directory used by tools like istanbul 18 | coverage 19 | 20 | # nyc test coverage 21 | .nyc_output 22 | 23 | # Grunt intermediate storage (http://gruntjs.com/creating-plugins#storing-task-files) 24 | .grunt 25 | 26 | # Bower dependency directory (https://bower.io/) 27 | bower_components 28 | 29 | # node-waf configuration 30 | .lock-wscript 31 | 32 | # Compiled binary addons (https://nodejs.org/api/addons.html) 33 | build/Release 34 | 35 | # Dependency directories 36 | node_modules/ 37 | jspm_packages/ 38 | 39 | # TypeScript v1 declaration files 40 | typings/ 41 | 42 | # Optional npm cache directory 43 | .npm 44 | 45 | # Optional eslint cache 46 | .eslintcache 47 | 48 | # Optional REPL history 49 | .node_repl_history 50 | 51 | # Output of 'npm pack' 52 | *.tgz 53 | 54 | # Yarn 55 | yarn-error.log 56 | .pnp/ 57 | .pnp.js 58 | 59 | # Yarn Integrity file 60 | .yarn-integrity 61 | 62 | # dotenv environment variables file 63 | .env 64 | 65 | # next.js build output 66 | .next 67 | 68 | # gatsby files 69 | .cache/ 70 | public 71 | 72 | # Mac files 73 | .DS_Store -------------------------------------------------------------------------------- /CODE_OF_CONDUCT.md: -------------------------------------------------------------------------------- 1 | # Contributor Covenant Code of Conduct 2 | 3 | ## Our Pledge 4 | 5 | In the interest of fostering an open and welcoming environment, we as contributors and maintainers pledge to making participation in our project and our community a harassment-free experience for everyone, regardless of age, body size, disability, ethnicity, gender identity and expression, level of experience, nationality, personal appearance, race, religion, or sexual identity and orientation. 6 | 7 | ## Our Standards 8 | 9 | Examples of behavior that contributes to creating a positive environment include: 10 | 11 | * Using welcoming and inclusive language 12 | * Being respectful of differing viewpoints and experiences 13 | * Gracefully accepting constructive criticism 14 | * Focusing on what is best for the community 15 | * Showing empathy towards other community members 16 | 17 | Examples of unacceptable behavior by participants include: 18 | 19 | * The use of sexualized language or imagery and unwelcome sexual attention or advances 20 | * Trolling, insulting/derogatory comments, and personal or political attacks 21 | * Public or private harassment 22 | * Publishing others' private information, such as a physical or electronic address, without explicit permission 23 | * Other conduct which could reasonably be considered inappropriate in a professional setting 24 | 25 | ## Our Responsibilities 26 | 27 | Project maintainers are responsible for clarifying the standards of acceptable behavior and are expected to take appropriate and fair corrective action in response to any instances of unacceptable behavior. 28 | 29 | Project maintainers have the right and responsibility to remove, edit, or reject comments, commits, code, wiki edits, issues, and other contributions that are not aligned to this Code of Conduct, or to ban temporarily or permanently any contributor for other behaviors that they deem inappropriate, threatening, offensive, or harmful. 30 | 31 | ## Scope 32 | 33 | This Code of Conduct applies both within project spaces and in public spaces when an individual is representing the project or its community. Examples of representing a project or community include using an official project e-mail address, posting via an official social media account, or acting as an appointed representative at an online or offline event. Representation of a project may be further defined and clarified by project maintainers. 34 | 35 | ## Enforcement 36 | 37 | Instances of abusive, harassing, or otherwise unacceptable behavior may be reported by contacting the project team at 30secondsofcode@gmail.com. The project team will review and investigate all complaints, and will respond in a way that it deems appropriate to the circumstances. The project team is obligated to maintain confidentiality with regard to the reporter of an incident. Further details of specific enforcement policies may be posted separately. 38 | 39 | Project maintainers who do not follow or enforce the Code of Conduct in good faith may face temporary or permanent repercussions as determined by other members of the project's leadership. 40 | 41 | ## Attribution 42 | 43 | This Code of Conduct is adapted from the [Contributor Covenant][homepage], version 1.4, available at [http://contributor-covenant.org/version/1/4][version] 44 | 45 | [homepage]: http://contributor-covenant.org 46 | [version]: http://contributor-covenant.org/version/1/4/ 47 | -------------------------------------------------------------------------------- /CONTRIBUTING.md: -------------------------------------------------------------------------------- 1 | # Contribution Guidelines 2 | 3 | **30 seconds of code** is powered by the community, so feel free to contribute in any way you can to help us! 4 | 5 | ## How you can help 6 | 7 | - Submit pull requests with new snippets (see guidelines below) or snippet updates (tags, descriptions, explanations, typos, examples, code improvements). 8 | - Open issues for things you want to see added, modified, discuss ideas or help out with existing issues. 9 | 10 | ## Ground rules 11 | 12 | Breaking any of these rules will result in your pull request being closed. Please follow these guidelines above all else: 13 | 14 | - **Always be polite and respectful to others** and try to follow the advice of the moderators/collaborators/owners. 15 | - **Only modify snippet files**, never modify the generated files in the `snippet_data` directory. 16 | - **Use the snippet template** to create new snippets, ensure they have the correct name and are in the correct location. 17 | - **Follow snippet format exactly**, otherwise your snippets will not be recognized correctly by the tools responsible for publishing them on the website. This includes such things as spacing and empty lines - if you accidentally make a mistake, consult the repository's [snippet template](snippet-template.md). 18 | - **Snippets should solve real-world problems**, no matter how simple and should be abstract enough to be applied to different scenarios. 19 | 20 | ## Snippet creation 21 | 22 | In order to create a new snippet, you should follow the steps below: 23 | 24 | - Create a copy of the [snippet template](snippet-template.md) in the `snippets` directory. 25 | - Change the name of the newly created file to the name of your snippet. 26 | - Edit the file, adding your snippet based on the guidelines. 27 | 28 | ## Snippet guidelines 29 | 30 | - Snippet must follow [these general writing guidelines](https://github.com/30-seconds/brand-and-design/blob/master/writing-guidelines.md). 31 | - Snippets must have all their frontmatter sections (title, tags etc.) filled. 32 | - Snippet titles must correspond to the filename and follow the language and repository's naming conventions. 33 | - Snippet tags must be comma-separated, contain a primary tag as seen on the website as their first tag. 34 | - Snippets must have their `firstSeen` dates formatted using [ISO 8601](https://en.wikipedia.org/wiki/ISO_8601). 35 | - Snippet descriptions must be short and to the point. Explain *what* the snippet does and detail *how* the snippet works and the language features used in it. 36 | - Snippet code and examples must be enclosed in appropriate, language-tagged blocks as shown in the snippet template, be short and use modern techniques and features. Also make sure to test your code before submitting. 37 | - If your snippet contains arguments with default parameters, explain what happens if they are omitted when calling the function and what the default case is. Specify default parameters for arguments only if necessary. 38 | - If your snippet uses recursion, use the `recursion` tag and explain the base cases. 39 | - Try to strike a balance between readability, brevity, and performance. 40 | - Always use soft tabs (2 spaces), never hard tabs. 41 | - Leave a single space after a comma (`,`) character (both in the description and code). 42 | - Define multiple variables on the same line, if possible. Use meaningful names (e.g. `letter` instead of `lt`) and follow existing conventions as seen in other snippets. Do not use trailing or leading underscores in variable names. 43 | - When describing snippets, refer to methods, using their full name. For example, use `Array.prototype.reduce()`, instead of `reduce()`. When using React Hooks, refer to the specific hooks with their full names, such as `useState()` and `useEffect()`. 44 | - When using `useState()`, try matching the name of the state variable to the function that sets it. For example, use `[isShown, setIsShown]` instead of `[isShown, setShown]`. When using `useEffect()`, only return a function if you have to clean up. In that case, name that function `cleanup()`. 45 | - Destructure your component's `props` whenever possible. If any of your props take default parameters, specify their default values in the destructured object. 46 | - Always use `const MyComponent = (props)` or `const MyComponent = ({ ... })` for function definitions. 47 | - Always use single quotes for string literals. Use template literals, instead, if necessary. 48 | - When rendering JSX, use double quotes, instead of single quotes. 49 | - Use strict equality checking (`===` and `!==` instead of `==` and `!=`). 50 | - Prefer using the ternary operator (`condition ? trueResult : falseResult`) instead of `if else` statements whenever possible. Avoid nesting ternary operators. 51 | - Never use `eval()`. 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For 392 | the avoidance of doubt, this paragraph does not form part of the 393 | public licenses. 394 | 395 | Creative Commons may be contacted at creativecommons.org. 396 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | > **IMPORTANT NOTICE:** 2 | > 3 | > As of May, 2023, all 30-seconds content repositories have been merged into [30-seconds-of-code](https://github.com/30-seconds/30-seconds-of-code). 4 | > 5 | > Please watch, star and follow relevant activity there. 6 | 7 | [![Logo](/logo.png)](https://30secondsofcode.org/react/p/1) 8 | 9 | # 30 seconds of code 10 | 11 | > Short React code snippets for all your development needs 12 | 13 | * Visit [our website](https://30secondsofcode.org) to view our snippet collection. 14 | * Use the [Search page](https://30secondsofcode.org/search) to find snippets that suit your needs. You can search by name, tag, language or using a snippet's description. Just start typing a term and see what comes up. 15 | * Browse the [React Snippet collection](https://30secondsofcode.org/react/p/1) to see all the snippets in this project or click individual tags at the top of the same page to narrow down your search to a specific tag. 16 | * Click on each snippet card to view the whole snippet, including code, explanation and examples. 17 | * You can use the button at the bottom of a snippet card to view the snippet in Codepen. 18 | * If you like the project, give it a star. It means a lot to the people maintaining it. 19 | 20 | ## Want to contribute? 21 | 22 | * If you want to help us improve, take a minute to read the [Contribution Guidelines](/CONTRIBUTING.md) first. 23 | * Use the [Snippet Template](/snippet-template.md) to add new snippets to the collection. 24 | * If you find a problem with a specific snippet, please [open an issue](https://github.com/30-seconds/30-seconds-of-react/issues/new). 25 | * If you find a problem with the website, please [report it in the web repository](https://github.com/30-seconds/30-seconds-web/issues/new). 26 | 27 | ## Credits 28 | 29 | * This repository is maintained by the [30 seconds of code organization on GitHub](https://github.com/30-seconds). 30 | * All snippets are licensed under the CC-BY-4.0 License, unless explicitly stated otherwise. 31 | * Logos, names and trademarks are not to be used without the explicit consent of the owners of the 30 seconds of code GitHub organization. 32 | * Our website is powered by [Netlify](https://www.netlify.com/), [Next.js](https://nextjs.org/) & [GitHub](https://github.com/). 33 | -------------------------------------------------------------------------------- /languageFix.jsx: -------------------------------------------------------------------------------- 1 | console.log('This file is here only to tag the repository language. Do not delete, please!'); 2 | -------------------------------------------------------------------------------- /logo.png: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/Chalarangelo/30-seconds-of-react/a5e673afbaddd31d6f80b2218ab16d0a82514cf5/logo.png -------------------------------------------------------------------------------- /snippet-template.md: -------------------------------------------------------------------------------- 1 | --- 2 | title: Component Name 3 | type: snippet 4 | tags: [components,state,effect] 5 | cover: image 6 | dateModified: 2021-06-13T05:00:00-04:00 7 | --- 8 | 9 | Explain briefly what the snippet does. 10 | 11 | - Explain briefly how the snippet works. 12 | - Use bullet points for your snippet's explanation. 13 | - Try to explain everything briefly but clearly. 14 | 15 | ```jsx 16 | const ComponentName = props => { 17 | const [state, setState] = React.useState(null); 18 | React.useEffect(() => { 19 | setState(0); 20 | }); 21 | return
{props}
; 22 | } 23 | ``` 24 | 25 | ```jsx 26 | ReactDOM.createRoot(document.getElementById('root')).render( 27 | 28 | ); 29 | ``` 30 | -------------------------------------------------------------------------------- /snippets/accordion.md: -------------------------------------------------------------------------------- 1 | --- 2 | title: Collapsible accordion 3 | type: snippet 4 | tags: [components,children,state] 5 | cover: beach-pineapple 6 | dateModified: 2021-10-13T19:29:39+02:00 7 | --- 8 | 9 | Renders an accordion menu with multiple collapsible content elements. 10 | 11 | - Define an `AccordionItem` component, that renders a ` 41 |
45 | {children} 46 |
47 | 48 | ); 49 | }; 50 | 51 | const Accordion = ({ defaultIndex, onItemClick, children }) => { 52 | const [bindIndex, setBindIndex] = React.useState(defaultIndex); 53 | 54 | const changeItem = itemIndex => { 55 | if (typeof onItemClick === 'function') onItemClick(itemIndex); 56 | if (itemIndex !== bindIndex) setBindIndex(itemIndex); 57 | }; 58 | const items = children.filter(item => item.type.name === 'AccordionItem'); 59 | 60 | return ( 61 | <> 62 | {items.map(({ props }) => ( 63 | changeItem(props.index)} 67 | children={props.children} 68 | /> 69 | ))} 70 | 71 | ); 72 | }; 73 | ``` 74 | 75 | ```jsx 76 | ReactDOM.createRoot(document.getElementById('root')).render( 77 | 78 | 79 | Lorem ipsum 80 | 81 | 82 | Dolor sit amet 83 | 84 | 85 | ); 86 | ``` 87 | -------------------------------------------------------------------------------- /snippets/alert.md: -------------------------------------------------------------------------------- 1 | --- 2 | title: Closable alert 3 | type: snippet 4 | tags: [components,state,effect] 5 | cover: flower-portrait-1 6 | dateModified: 2021-01-07T23:57:13+02:00 7 | --- 8 | 9 | Renders an alert component with `type` prop. 10 | 11 | - Use the `useState()` hook to create the `isShown` and `isLeaving` state variables and set both to `false` initially. 12 | - Define `timeoutId` to keep the timer instance for clearing on component unmount. 13 | - Use the `useEffect()` hook to update the value of `isShown` to `true` and clear the interval by using `timeoutId` when the component is unmounted. 14 | - Define a `closeAlert` function to set the component as removed from the DOM by displaying a fading out animation and set `isShown` to `false` via `setTimeout()`. 15 | 16 | ```css 17 | @keyframes leave { 18 | 0% { opacity: 1 } 19 | 100% { opacity: 0 } 20 | } 21 | 22 | .alert { 23 | padding: 0.75rem 0.5rem; 24 | margin-bottom: 0.5rem; 25 | text-align: left; 26 | padding-right: 40px; 27 | border-radius: 4px; 28 | font-size: 16px; 29 | position: relative; 30 | } 31 | 32 | .alert.warning { 33 | color: #856404; 34 | background-color: #fff3cd; 35 | border-color: #ffeeba; 36 | } 37 | 38 | .alert.error { 39 | color: #721c24; 40 | background-color: #f8d7da; 41 | border-color: #f5c6cb; 42 | } 43 | 44 | .alert.leaving { 45 | animation: leave 0.5s forwards; 46 | } 47 | 48 | .alert .close { 49 | position: absolute; 50 | top: 0; 51 | right: 0; 52 | padding: 0 0.75rem; 53 | color: #333; 54 | border: 0; 55 | height: 100%; 56 | cursor: pointer; 57 | background: none; 58 | font-weight: 600; 59 | font-size: 16px; 60 | } 61 | 62 | .alert .close::after { 63 | content: 'x'; 64 | } 65 | ``` 66 | 67 | ```jsx 68 | const Alert = ({ isDefaultShown = false, timeout = 250, type, message }) => { 69 | const [isShown, setIsShown] = React.useState(isDefaultShown); 70 | const [isLeaving, setIsLeaving] = React.useState(false); 71 | 72 | let timeoutId = null; 73 | 74 | React.useEffect(() => { 75 | setIsShown(true); 76 | return () => { 77 | clearTimeout(timeoutId); 78 | }; 79 | }, [isDefaultShown, timeout, timeoutId]); 80 | 81 | const closeAlert = () => { 82 | setIsLeaving(true); 83 | timeoutId = setTimeout(() => { 84 | setIsLeaving(false); 85 | setIsShown(false); 86 | }, timeout); 87 | }; 88 | 89 | return ( 90 | isShown && ( 91 |
95 |
98 | ) 99 | ); 100 | }; 101 | ``` 102 | 103 | ```jsx 104 | ReactDOM.createRoot(document.getElementById('root')).render( 105 | 106 | ); 107 | ``` 108 | -------------------------------------------------------------------------------- /snippets/auto-link.md: -------------------------------------------------------------------------------- 1 | --- 2 | title: Automatic text linking 3 | type: snippet 4 | tags: [components,fragment,regexp] 5 | author: chalarangelo 6 | cover: red-petals 7 | dateModified: 2020-11-03T20:42:15+02:00 8 | --- 9 | 10 | Renders a string as plaintext, with URLs converted to appropriate link elements. 11 | 12 | - Use `String.prototype.split()` and `String.prototype.match()` with a regular expression to find URLs in a string. 13 | - Return matched URLs rendered as `` elements, dealing with missing protocol prefixes if necessary. 14 | - Render the rest of the string as plaintext. 15 | 16 | ```jsx 17 | const AutoLink = ({ text }) => { 18 | const delimiter = /((?:https?:\/\/)?(?:(?:[a-z0-9]?(?:[a-z0-9\-]{1,61}[a-z0-9])?\.[^\.|\s])+[a-z\.]*[a-z]+|(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)(?:\.(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)){3})(?::\d{1,5})*[a-z0-9.,_\/~#&=;%+?\-\\(\\)]*)/gi; 19 | 20 | return ( 21 | <> 22 | {text.split(delimiter).map(word => { 23 | const match = word.match(delimiter); 24 | if (match) { 25 | const url = match[0]; 26 | return ( 27 | {url} 28 | ); 29 | } 30 | return word; 31 | })} 32 | 33 | ); 34 | }; 35 | ``` 36 | 37 | ```jsx 38 | ReactDOM.createRoot(document.getElementById('root')).render( 39 | 40 | ); 41 | ``` 42 | -------------------------------------------------------------------------------- /snippets/callto.md: -------------------------------------------------------------------------------- 1 | --- 2 | title: Callable telephone link 3 | type: snippet 4 | tags: [components] 5 | author: chalarangelo 6 | unlisted: true 7 | cover: rabbit-call 8 | dateModified: 2021-01-04T12:32:47+02:00 9 | --- 10 | 11 | Renders a link formatted to call a phone number (`tel:` link). 12 | 13 | - Use `phone` to create a `` element with an appropriate `href` attribute. 14 | - Render the link with `children` as its content. 15 | 16 | ```jsx 17 | const Callto = ({ phone, children }) => { 18 | return {children}; 19 | }; 20 | ``` 21 | 22 | ```jsx 23 | ReactDOM.createRoot(document.getElementById('root')).render( 24 | Call me! 25 | ); 26 | ``` 27 | -------------------------------------------------------------------------------- /snippets/carousel.md: -------------------------------------------------------------------------------- 1 | --- 2 | title: Carousel 3 | type: snippet 4 | tags: [components,children,state,effect] 5 | cover: shell-focus 6 | dateModified: 2020-11-03T20:42:15+02:00 7 | --- 8 | 9 | Renders a carousel component. 10 | 11 | - Use the `useState()` hook to create the `active` state variable and give it a value of `0` (index of the first item). 12 | - Use the `useEffect()` hook to update the value of `active` to the index of the next item, using `setTimeout()`. 13 | - Compute the `className` for each carousel item while mapping over them and applying it accordingly. 14 | - Render the carousel items using `React.cloneElement()` and pass down `...rest` along with the computed `className`. 15 | 16 | ```css 17 | .carousel { 18 | position: relative; 19 | } 20 | 21 | .carousel-item { 22 | position: absolute; 23 | visibility: hidden; 24 | } 25 | 26 | .carousel-item.visible { 27 | visibility: visible; 28 | } 29 | ``` 30 | 31 | ```jsx 32 | const Carousel = ({ carouselItems, ...rest }) => { 33 | const [active, setActive] = React.useState(0); 34 | let scrollInterval = null; 35 | 36 | React.useEffect(() => { 37 | scrollInterval = setTimeout(() => { 38 | setActive((active + 1) % carouselItems.length); 39 | }, 2000); 40 | return () => clearTimeout(scrollInterval); 41 | }); 42 | 43 | return ( 44 |
45 | {carouselItems.map((item, index) => { 46 | const activeClass = active === index ? ' visible' : ''; 47 | return React.cloneElement(item, { 48 | ...rest, 49 | className: `carousel-item${activeClass}` 50 | }); 51 | })} 52 |
53 | ); 54 | }; 55 | ``` 56 | 57 | ```jsx 58 | ReactDOM.createRoot(document.getElementById('root')).render( 59 | carousel item 1, 62 |
carousel item 2
, 63 |
carousel item 3
64 | ]} 65 | /> 66 | ); 67 | ``` 68 | -------------------------------------------------------------------------------- /snippets/collapse.md: -------------------------------------------------------------------------------- 1 | --- 2 | title: Collapsible content 3 | type: snippet 4 | tags: [components,children,state] 5 | cover: washed-ashore 6 | dateModified: 2021-10-13T19:29:39+02:00 7 | --- 8 | 9 | Renders a component with collapsible content. 10 | 11 | - Use the `useState()` hook to create the `isCollapsed` state variable. Give it an initial value of `collapsed`. 12 | - Use the ` 43 |
47 | {children} 48 |
49 | 50 | ); 51 | }; 52 | ``` 53 | 54 | ```jsx 55 | ReactDOM.createRoot(document.getElementById('root')).render( 56 | 57 |

This is a collapse

58 |

Hello world!

59 | 60 | ); 61 | ``` 62 | -------------------------------------------------------------------------------- /snippets/controlled-input.md: -------------------------------------------------------------------------------- 1 | --- 2 | title: Controlled input field 3 | type: snippet 4 | tags: [components,input] 5 | cover: digital-nomad-5 6 | dateModified: 2020-11-03T21:08:39+02:00 7 | --- 8 | 9 | Renders a controlled `` element that uses a callback function to inform its parent about value updates. 10 | 11 | - Use the `value` passed down from the parent as the controlled input field's value. 12 | - Use the `onChange` event to fire the `onValueChange` callback and send the new value to the parent. 13 | - The parent must update the input field's `value` prop in order for its value to change on user input. 14 | 15 | ```jsx 16 | const ControlledInput = ({ value, onValueChange, ...rest }) => { 17 | return ( 18 | onValueChange(value)} 21 | {...rest} 22 | /> 23 | ); 24 | }; 25 | ``` 26 | 27 | ```jsx 28 | const Form = () => { 29 | const [value, setValue] = React.useState(''); 30 | 31 | return ( 32 | 38 | ); 39 | }; 40 | 41 | ReactDOM.createRoot(document.getElementById('root')).render( 42 |
43 | ); 44 | ``` 45 | -------------------------------------------------------------------------------- /snippets/count-down.md: -------------------------------------------------------------------------------- 1 | --- 2 | title: Countdown timer 3 | type: snippet 4 | tags: [components,state] 5 | cover: sea-view-2 6 | dateModified: 2021-10-13T19:29:39+02:00 7 | --- 8 | 9 | Renders a countdown timer that prints a message when it reaches zero. 10 | 11 | - Use the `useState()` hook to create a state variable to hold the time value. Initialize it from the props and destructure it into its components. 12 | - Use the `useState()` hook to create the `paused` and `over` state variables, used to prevent the timer from ticking if it's paused or the time has run out. 13 | - Create a method `tick`, that updates the time values based on the current value (i.e. decreasing the time by one second). 14 | - Create a method `reset`, that resets all state variables to their initial states. 15 | - Use the the `useEffect()` hook to call the `tick` method every second via the use of `setInterval()` and use `clearInterval()` to clean up when the component is unmounted. 16 | - Use `String.prototype.padStart()` to pad each part of the time array to two characters to create the visual representation of the timer. 17 | 18 | ```jsx 19 | const CountDown = ({ hours = 0, minutes = 0, seconds = 0 }) => { 20 | const [paused, setPaused] = React.useState(false); 21 | const [over, setOver] = React.useState(false); 22 | const [[h, m, s], setTime] = React.useState([hours, minutes, seconds]); 23 | 24 | const tick = () => { 25 | if (paused || over) return; 26 | if (h === 0 && m === 0 && s === 0) setOver(true); 27 | else if (m === 0 && s === 0) { 28 | setTime([h - 1, 59, 59]); 29 | } else if (s == 0) { 30 | setTime([h, m - 1, 59]); 31 | } else { 32 | setTime([h, m, s - 1]); 33 | } 34 | }; 35 | 36 | const reset = () => { 37 | setTime([parseInt(hours), parseInt(minutes), parseInt(seconds)]); 38 | setPaused(false); 39 | setOver(false); 40 | }; 41 | 42 | React.useEffect(() => { 43 | const timerID = setInterval(() => tick(), 1000); 44 | return () => clearInterval(timerID); 45 | }); 46 | 47 | return ( 48 |
49 |

{`${h.toString().padStart(2, '0')}:${m 50 | .toString() 51 | .padStart(2, '0')}:${s.toString().padStart(2, '0')}`}

52 |
{over ? "Time's up!" : ''}
53 | 56 | 57 |
58 | ); 59 | }; 60 | ``` 61 | 62 | ```jsx 63 | ReactDOM.createRoot(document.getElementById('root')).render( 64 | 65 | ); 66 | ``` 67 | -------------------------------------------------------------------------------- /snippets/data-list.md: -------------------------------------------------------------------------------- 1 | --- 2 | title: Data list 3 | type: snippet 4 | tags: [components] 5 | cover: interior-14 6 | dateModified: 2020-11-03T21:26:34+02:00 7 | --- 8 | 9 | Renders a list of elements from an array of primitives. 10 | 11 | - Use the value of the `isOrdered` prop to conditionally render an `
    ` or a `
      ` list. 12 | - Use `Array.prototype.map()` to render every item in `data` as a `
    • ` element with an appropriate `key`. 13 | 14 | ```jsx 15 | const DataList = ({ isOrdered = false, data }) => { 16 | const list = data.map((val, i) =>
    • {val}
      • ); 17 | return isOrdered ?
        {list}
      :
        {list}
      ; 18 | }; 19 | ``` 20 | 21 | ```jsx 22 | const names = ['John', 'Paul', 'Mary']; 23 | ReactDOM.createRoot(document.getElementById('root')).render( 24 | <> 25 | 26 | 27 | 28 | ); 29 | ``` 30 | -------------------------------------------------------------------------------- /snippets/data-table.md: -------------------------------------------------------------------------------- 1 | --- 2 | title: Data table 3 | type: snippet 4 | tags: [components] 5 | cover: armchair 6 | dateModified: 2020-11-03T21:26:34+02:00 7 | --- 8 | 9 | Renders a table with rows dynamically created from an array of primitives. 10 | 11 | - Render a `` element with two columns (`ID` and `Value`). 12 | - Use `Array.prototype.map()` to render every item in `data` as a `` element with an appropriate `key`. 13 | 14 | ```jsx 15 | const DataTable = ({ data }) => { 16 | return ( 17 |
      18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | {data.map((val, i) => ( 26 | 27 | 28 | 29 | 30 | ))} 31 | 32 |
      IDValue
      {i}{val}
      33 | ); 34 | }; 35 | ``` 36 | 37 | ```jsx 38 | const people = ['John', 'Jesse']; 39 | ReactDOM.createRoot(document.getElementById('root')).render( 40 | 41 | ); 42 | ``` 43 | -------------------------------------------------------------------------------- /snippets/file-drop.md: -------------------------------------------------------------------------------- 1 | --- 2 | title: File drag and drop area 3 | type: snippet 4 | tags: [components,input,state,effect,event] 5 | author: chalarangelo 6 | cover: man-red-sunset 7 | dateModified: 2021-10-13T19:29:39+02:00 8 | --- 9 | 10 | Renders a file drag and drop component for a single file. 11 | 12 | - Create a ref, called `dropRef` and bind it to the component's wrapper. 13 | - Use the `useState()` hook to create the `drag` and `filename` variables. Initialize them to `false` and `''` respectively. 14 | - The variables `dragCounter` and `drag` are used to determine if a file is being dragged, while `filename` is used to store the dropped file's name. 15 | - Create the `handleDrag`, `handleDragIn`, `handleDragOut` and `handleDrop` methods to handle drag and drop functionality. 16 | - `handleDrag` prevents the browser from opening the dragged file. `handleDragIn` and `handleDragOut` handle the dragged file entering and exiting the component. `handleDrop` handles the file being dropped and passes it to `onDrop`. 17 | - Use the `useEffect()` hook to handle each of the drag and drop events using the previously created methods. 18 | 19 | ```css 20 | .filedrop { 21 | min-height: 120px; 22 | border: 3px solid #d3d3d3; 23 | text-align: center; 24 | font-size: 24px; 25 | padding: 32px; 26 | border-radius: 4px; 27 | } 28 | 29 | .filedrop.drag { 30 | border: 3px dashed #1e90ff; 31 | } 32 | 33 | .filedrop.ready { 34 | border: 3px solid #32cd32; 35 | } 36 | ``` 37 | 38 | ```jsx 39 | const FileDrop = ({ onDrop }) => { 40 | const [drag, setDrag] = React.useState(false); 41 | const [filename, setFilename] = React.useState(''); 42 | let dropRef = React.createRef(); 43 | let dragCounter = 0; 44 | 45 | const handleDrag = e => { 46 | e.preventDefault(); 47 | e.stopPropagation(); 48 | }; 49 | 50 | const handleDragIn = e => { 51 | e.preventDefault(); 52 | e.stopPropagation(); 53 | dragCounter++; 54 | if (e.dataTransfer.items && e.dataTransfer.items.length > 0) setDrag(true); 55 | }; 56 | 57 | const handleDragOut = e => { 58 | e.preventDefault(); 59 | e.stopPropagation(); 60 | dragCounter--; 61 | if (dragCounter === 0) setDrag(false); 62 | }; 63 | 64 | const handleDrop = e => { 65 | e.preventDefault(); 66 | e.stopPropagation(); 67 | setDrag(false); 68 | if (e.dataTransfer.files && e.dataTransfer.files.length > 0) { 69 | onDrop(e.dataTransfer.files[0]); 70 | setFilename(e.dataTransfer.files[0].name); 71 | e.dataTransfer.clearData(); 72 | dragCounter = 0; 73 | } 74 | }; 75 | 76 | React.useEffect(() => { 77 | let div = dropRef.current; 78 | div.addEventListener('dragenter', handleDragIn); 79 | div.addEventListener('dragleave', handleDragOut); 80 | div.addEventListener('dragover', handleDrag); 81 | div.addEventListener('drop', handleDrop); 82 | return () => { 83 | div.removeEventListener('dragenter', handleDragIn); 84 | div.removeEventListener('dragleave', handleDragOut); 85 | div.removeEventListener('dragover', handleDrag); 86 | div.removeEventListener('drop', handleDrop); 87 | }; 88 | }); 89 | 90 | return ( 91 |
      97 | {filename && !drag ?
      {filename}
      :
      Drop a file here!
      } 98 |
      99 | ); 100 | }; 101 | ``` 102 | 103 | ```jsx 104 | ReactDOM.createRoot(document.getElementById('root')).render( 105 | 106 | ); 107 | ``` 108 | -------------------------------------------------------------------------------- /snippets/lazy-load-image.md: -------------------------------------------------------------------------------- 1 | --- 2 | title: Lazy-loading image 3 | type: snippet 4 | tags: [components,effect,state] 5 | cover: strawberries 6 | author: chalarangelo 7 | dateModified: 2022-07-29T05:00:00-04:00 8 | --- 9 | 10 | Renders an image that supports lazy loading. 11 | 12 | - Use the `useState()` hook to create a stateful value that indicates if the image has been loaded. 13 | - Use the `useEffect()` hook to check if the `HTMLImageElement.prototype` contains `'loading'`, effectively checking if lazy loading is supported natively. If not, create a new `IntersectionObserver` and use `IntersectionObserver.observer()` to observer the `` element. Use the `return` value of the hook to clean up when the component unmounts. 14 | - Use the `useCallback()` hook to memoize a callback function for the `IntersectionObserver`. This callback will update the `isLoaded` state variable and use `IntersectionObserver.disconnect()` to disconnect the `IntersectionObserver` instance. 15 | - Use the `useRef()` hook to create two refs. One will hold the `` element and the other the `IntersectionObserver` instance, if necessary. 16 | - Finally, render the `` element with the given attributes. Apply `loading='lazy'` to make it load lazily, if necessary. Use `isLoaded` to determine the value of the `src` attribute. 17 | 18 | ```jsx 19 | const LazyLoadImage = ({ 20 | alt, 21 | src, 22 | className, 23 | loadInitially = false, 24 | observerOptions = { root: null, rootMargin: '200px 0px' }, 25 | ...props 26 | }) => { 27 | const observerRef = React.useRef(null); 28 | const imgRef = React.useRef(null); 29 | const [isLoaded, setIsLoaded] = React.useState(loadInitially); 30 | 31 | const observerCallback = React.useCallback( 32 | entries => { 33 | if (entries[0].isIntersecting) { 34 | observerRef.current.disconnect(); 35 | setIsLoaded(true); 36 | } 37 | }, 38 | [observerRef] 39 | ); 40 | 41 | React.useEffect(() => { 42 | if (loadInitially) return; 43 | 44 | if ('loading' in HTMLImageElement.prototype) { 45 | setIsLoaded(true); 46 | return; 47 | } 48 | 49 | observerRef.current = new IntersectionObserver( 50 | observerCallback, 51 | observerOptions 52 | ); 53 | observerRef.current.observe(imgRef.current); 54 | return () => { 55 | observerRef.current.disconnect(); 56 | }; 57 | }, []); 58 | 59 | return ( 60 | {alt} 68 | ); 69 | }; 70 | ``` 71 | 72 | ```jsx 73 | ReactDOM.createRoot(document.getElementById('root')).render( 74 | 78 | ); 79 | ``` 80 | -------------------------------------------------------------------------------- /snippets/limited-textarea.md: -------------------------------------------------------------------------------- 1 | --- 2 | title: Textarea with character limit 3 | type: snippet 4 | tags: [components,state,callback,event] 5 | cover: flower-portrait-2 6 | dateModified: 2021-10-13T19:29:39+02:00 7 | --- 8 | 9 | Renders a textarea component with a character limit. 10 | 11 | - Use the `useState()` hook to create the `content` state variable. Set its value to that of `value` prop, trimmed down to `limit` characters. 12 | - Create a method `setFormattedContent`, which trims the content down to `limit` characters and memoize it, using the `useCallback()` hook. 13 | - Bind the `onChange` event of the `