MDN Web Docs
@MozDevNet
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The official MDN Web Docs account. We deliver the best web docs around.
Joined March 2013
CSS in 2025: What's new? 🤔. Let's unpack this together in our May community call! Our Spotlight contributor, @YashRaj49744398 will share and demo new updates, and how to use the new functions and rulesets!. 🗓️ Wednesday, May 28th at 17:00 CET.💬 MDN Web Docs Discord. Join us! 👇
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MDN as a website isn't going anywhere right now. The team is smaller, but the site exists and isn't going away. We will be working with partners and community members to find the right ways to move it forward given our new structure at Mozilla.
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A new year, a new MDN! 🎉. If you’ve accessed the MDN website today, you probably noticed that it looks quite different. We've made some changes to create a clean and inviting website that makes navigating our content as easy as possible.
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Today is the BIG DAY. We're 15 years young! 🥳. From humble beginnings, rising out of the ashes of Netscape DevEdge, we have grown to be one of the best-respected web platform documentation sites out there. #MDNTurns15
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Hello, Angular! . Everything you need to get started with @angular is now live on MDN. We look at what Angular has to offer, install the prerequisites and set up a sample app, and look at Angular's basic architecture. 📖 👩🏾💻 .
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JavaScript's date object has been tricky for years, but that will change soon. The NEW Temporal API brings,.🌍 Easily handle time zones.📆 Precise date math.🕒 Parse ISO strings without errors.⌛ Durations, date ranges, and more. Start exploring 👇.
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In early 2005, a small team of idealists set out to create a new, free, community-built online resource for all Web developers. As we approach our 1️⃣5️⃣th year on July 23 - we want to know what you love about MDN and how MDN has helped you over the years.
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Firefox 7⃣8⃣ enables link rel=”preload” support. The preload value of the <link> element's rel attribute lets you declare fetch requests in the HTML's <head>, specifying resources before browsers' rendering kicks in.
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MDN is going .dev!.We’re launching this week to serve as a resource for open source contributions to MDN. Over time, we’ll expand our .dev presence, so watch this space to find out what’s next.
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We're excited to bring together @Microsoft, @Google, @w3c and @Samsung to create the best cross-browser docs:
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🎉 New compatibility tables are coming to MDN TOMORROW! 🎉.After several months of beta testing our new, clearer (more colorful) browser compat tables, we're pushing them live for all tomorrow! What do you think of them?.
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Yari has landed! 🎉. After several intense months of work on such a significant change, the day is finally upon us: MDN Web Docs’ new platform (codenamed Yari) is finally launched!
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We made our web compatibility tables machine-readable, so that tools like @code could use them in Visual Studio: Thanks to all who made that happen!.
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Are you still not using JavaScript Sets?. Discover ↓.✨ set.union().✨ set.intersection().✨ set.difference(). See how sets might make your data efficient. Dive in! 👇.
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🚨Coming soon to MDN compatibility tables and @caniuse🚨. No more questions about when a Web API was supported. As of today, all 7,000+ Web APIs tracked by MDN browser compat data are set to version numbers, contributed by @Google @OpenWebDocs and others
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We've started a YouTube channel! .8 videos have been published so far. They come in two series:. about:web – series on web technologies.Firefox – series on browser tools. 📽️🎞️
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🎉 IT HAPPENED! 🎉 Firefox 52 update is released! WebAssembly, CSS Grid, and (for all us devs) the Grid Inspector!
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Announcing interactive examples on MDN! 👏. We’ve just finished adding interactive examples for the JavaScript and CSS reference pages. Here's how we got here and what we learned on the way:
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H*ARRAY* 🎉🎉. JavaScript is 23 years old this week. We’re EMBERrassed for not remEMBERing. Learn how to program in JavaScript with our guides and tutorials.
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With new speed, comes a new look! New Dev Edition is twice as fast, a redesigned UI, all our dev tools, and more:
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It's finally here - the new MDN Browser Compatibility Report. 🎉🎉. The report is a deeper dive into issues, attempting to identify specific issues causing a lot of frustration and what could be done to improve the situation. 📖Read the report here:
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This is the web you know, and build on. 🛠️. A great visual by @HeyNina101 @SketechWorld, covering HTML & CSS to TCP & TLS - the core layers that keep everything running.
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Our Svelte tutorial is now live! 📖 . We provide a quick introduction to the Svelte framework, how it works and what sets it apart from the rest of the frameworks and tools we've seen so far.
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Using custom accordions? There's an easier way! 🪗. The <details> element now has a name attribute with support across all major browsers. ✨ No more custom handling for UI accordions.✨ Less code to maintain.✨ Native browser support. Try now 👇.
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Firefox 89 is here! 🔥🦊. ⌨️ Better keyboard navigation for editable BoxModel properties in the Inspector panel.🔥 The long-awaited top-level await keyword for JavaScript modules is now enabled .✔️ The type() function for image-set() has been implemented
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JavaScript's date object has been tricky for years, but that will change soon. The NEW Temporal API brings,.🌍 Easily handle time zones.📆 Precise date math.🕒 Parse ISO strings without errors.⌛ Durations, date ranges, and more. Start exploring 👇.
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Found the perfect color? Grab it:.1. Select Eyedropper tool from the Web Developer Menu. Select the color!.2. Click the color sample next to a CSS color setting. When the color picker opens, click the eyedropper icon under the color swatch. Select the color!. 🎨 Look at that!
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Our Web Docs have helped many people. 📖💻. Pay it forward and contribute one day or one year! 🎉. No coding required, just bring a passion for building a more inclusive 🤝 diverse community.
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ICYMI ⚠️. JavaScipt date object has been tricky for years, and it's changing soon. The NEW Temporal API brings,.🌍 Easily handle time zones.📆 Precise date math.🕒 Parse ISO strings without errors.⌛ Durations, date ranges, and more. Start exploring 👇.
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Have a long webpage or infinite scroll? 📃. Apply content-visibility to sections of the page to delay rendering until they're visible, resulting in faster initial load times. Once the content scrolls into view, it gets rendered automatically. Use now 👇.
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You want to learn.Use MDN . #100DaysofCode.
you want to learn JavaScript.Be consistent. you want to learn Python.Be consistent. you want to learn Rust .Be consistent. you want to learn PHP .Be consistent. you want to learn Java .Be consistent. you want to learn Go.Be consistent . Consistent is the key to learn anything.
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CSS Grid is changing graphic design on the web forever. See how @Jensimmons uses CSS Grid to create a responsive Mondrian: #CSSGrid #CSS
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TIL: Compression Dictionary Transport 💡. A new HTTP feature that can dramatically shrink the size of your responses, especially when serving content that changes often but includes a lot of repeated structure (think: JSON, JS, CSS). Learn more 👇.
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We’re excited that Microsoft will be further expanding their content contributions to MDN Web Docs! #msedgesummit.
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Last week, Mozilla announced some difficult changes and we would like to outline how they will impact our MDN platform moving forward. First things first - MDN is not going away.
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What are your favorite Twitter accounts to follow for web developer tips and insights?.We're big fans of:.@jensimmons .@rachelandrew .@adactio (and @adactioLinks).@smashingmag .@CodeNewbies .Let us know yours!.
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Firefox 90 is here! 🔥 🦊 . ✔️ Private class static and instance fields and methods are now supported by default. ✔️ The HTTP fetch metadata request headers (Sec-Fetch-*) are now supported. ❌ FTP has now been removed from Firefox .
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Flight attendant: Is there a doctor onboard?. Dad: *nudging me* that should've been you. Me: Not now Dad. Dad: Not asking for a Developer to help, are they?. Me: Dad, it's a medical emergency. Dad: Go and see if “Debugging" helps.
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❗️Coming Soon -- MDN Plus❗️. A new premium service with monthly technical deep dives written by industry experts and powerful new features to personalize your MDN experience. 🎉
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What's coming in Firefox 52 in 3 weeks? See our release notes for grid, devtools, and more amazingness: #firefox
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We're excited to launch AI Help - an interactive coding companion integrated with MDN in collaboration with @supabase! Find solutions, learn more efficiently, and discover MDN docs for context. Learn more about AI Help on the MDN blog:. #MDNBlogUpdate.
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The new Flexbox Inspector, created by Firefox DevTools, helps developers understand the sizing, positioning, and nesting of Flexbox elements. Here's what into making this useful tool: #flexbox.
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From Firefox 59 onwards, calc() functions ( are now supported inside color functions and media queries.
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WebAssembly is a low-level language designed to run alongside JavaScript. It allows languages to compile to the web with near-native performance. WebAssembly Studio is an online IDE that helps you learn and teach others. Check it out:
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The time has come for Kuma — the platform that powers MDN Web Docs — to evolve. We're updating from a MySQL database to being hosted in a @GitHub repository. ✅ Less developer maintenance burden.✅ Better community bldg.✅ Improved front-end architecture.
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New dev and not sure where to start? 🆘 . Our learning pathway can provide you with a structured course that will teach you all you need to know to become a front-end web developer.
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Want to contribute to MDN Web Docs? We would love your help keeping up the best docs on the web. Even if you don't have coding experience, you can learn a lot from doing editorial reviews! If you have dev friends who might be interested, please RT:
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Which is better: Flexbox or Grid? @jensimmons explains the differences and how they can work together in the new Layout Land channel:.
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Announcing the new Playground on MDN for live previews of HTML, CSS, and JavaScript!🚀🌟. Get hands-on with embedded examples to understand how features work through live interaction. Find out more about the Playground on the MDN blog:.#MDNBlogUpdate.
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Use the new @Firefox Side View extension to review MDN docs as you're building your site! Read about (and get) the new Side View extension: #DevTools #webdev #webdevelopment #CodeNewbie #developertools #docs
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👉 MDN needs your help! 👈.You know all those amazing interactive CSS examples that we recently added to the site (thanks to all who contributed)? We're doing HTML ones now, and you can help make it happen!. Find out what's involved and how to start:
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Today we are launching the second edition of the MDN Web Developer Needs Assessment! 🎉. Web developers and designers, we need to hear from you. This is your opportunity to tell us about your needs and frustrations with the web. 💻:
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Tip: Change SVG images using CSS filters!.We have an interactive demo you can play with to see how it works: #CSS #SVG #webdevelopment
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As of November 2, 2020, The Yari beta is open. 🎉🤝. Find out how you can get involved, what kind of feedback we're looking for, and where you can put it.
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Intl.Segmenter is now supported in all major browsers!. Build locale-aware UI and applications. Splits text into meaningful units based on the locale, this ensures that your app can handle non-Latin text, like Japanese or Hindi, with precision. Try now 👇.
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💯 . Our JavaScript tutorial is pretty good:
Don't stop after HTML and CSS, yes Javascript is overwhelming and tough. Go bit by bit, but don't quit there. I made this mistake twice, you shouldn't.
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We’re thrilled to announce the launch of MDN Curriculum! 🎉.A structured roadmap for front-end development learning, it’s an excellent resource for both students & educators. Discover how to make the most of it in our blog post.
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What's the difference between Flexbox and CSS Grid? @jensimmons talks about it in the newest video in Layout Land:
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JavaScript’s Map is a powerful data structure designed for key-value pairs, offering better performance and flexibility than plain objects in many cases. Key Advantages:.✅ Preserves Key Order.✅ Flexible Key Types.✅ Better Performance. Give it a try! ↓.
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We are thrilled to announce our partnership with @scrimba! 🥁. Together, we're enhancing the learning experience for web developers. Dive into high-quality content aligned with the MDN Curriculum. See what we have for you 👇.
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Want to learn how to debug your JavaScript? Check out the new section in the Developer Playground: #JavaScript.
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Firefox 7️⃣9️⃣ has landed! . 🔘Promise.any() is now available .🔘The Accessibility Inspector is automatically turned on when you access its tab.🔘SharedArrayBuffer has been re-enabled in a post-Spectre-safe manner.
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No lies. 💯.
MDN (@MozDevNet) is the best resource for answering specific questions you may have about HTML, CSS, or JavaScript.
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We’ve made a lot of progress on moving forward with MDN Web Docs in the last couple of months, and we wanted to share where we are headed in the short to mid-term, starting with our editorial strategy and renewed efforts around community participation.
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Forging Better Tools for the Web: A Firefox DevTools Retrospective:
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What you probably know:.✅ 200 OK.🔀 301 Moved Permanently.⚠️ 404 Not Found.⛔ 500 Internal Server Error. What you might not:.🫖 418 I'm a teapot.💾 206 Partial Content.🔓 451 Unavailable for Legal Reasons. Get a deep dive into status codes ↓.
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We’re delighted to announce that the HTTP Observatory’s new home is MDN! 🎉. The MDN HTTP Observatory tests website compliance with security best practices and lets you enhance your web security with insights from over 6.9 million scans. 🔒. Test now 👇.🔗
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Interop 2025 is here; a collaboration between browser and platform vendors to provide users and web devs with quality implementations of the web. 💻. Key Focus Areas:.✨ Storage Access.✨ Web Compat.✨ WebRTC.✨ Removing Mutation Events. Read more 👇.
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Firefox 91 is here! 🦊 🔥. ✔️ The Visual Viewport API is now enabled by default on desktop releases . ✔️ Intl.DateTimeFormat object additions 📆 ⏰ . ❌ The non-standard -moz-outline-radius property has been removed . 🔒 Gamepad API is now protected.
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Home for the holidays? 🦃 🎄 🧨 . Why not contribute to MDN Web Docs. 🙌🏾. No coding required, just bring a passion for building a more inclusive 🤝 diverse community.
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At the end of 2020, we launched our new Yari platform and today, we are proud to announce the launch of the @OpenWebDocs organization! A collective project designed to support a community of technical writers.
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Are you still not using JavaScript Sets? 🤔. Discover ↓.✨ set.union().✨ set.intersection().✨ set.difference(). See how sets might make your data efficient. Dive in! 🔗.
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Have a long webpage or infinite scroll? 📃. Apply content-visibility to sections of the page to delay rendering until they're visible, resulting in faster initial load times. Once the content scrolls into view, it gets rendered automatically. Use now 👇.
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How to use CSS Grid to make responsive layouts like this fancy rotated design, which straightens out at smaller screens. @JenSimmons explains in this video:
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Are you still not using JavaScript Sets?. Discover ↓.✨ set.union().✨ set.intersection().✨ set.difference(). See how sets might make your data efficient. Dive in! 👇.
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When streaming free video online, the standard H.264 codec costs money, which means "free" video isn't really free. We're big fans of AV1, because it's royalty-free and has great compression. Learn about it:
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Happy New Year to all our followers, supporters, contributors and friends. Looking forward to loads more in 2021! 💥💥🎇
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Get a preview of the WebAssembly Explorer: WebAssembly launches in Firefox 52 this week. #WASM #WebAssembly
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Are you still not using JavaScript Sets?. Discover ↓.✨ set.union().✨ set.intersection().✨ set.difference(). See how sets might make your data efficient. Dive in! 👇.
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MDN Web Docs is starting a journey of bringing a customised premium experience to our readers. Today, we are excited to announce the release of #MDNPlus in the US and Canada, opening to more countries in the coming months!
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Need a Fetch refresher? ⛲. Fetch API offers cleaner, promise-based syntax, better error handling, and async/await support. You can:.🔒 Add tokens & content types.📮 Make POST requests.🚅 Manage large data sets efficiently. Learn more 👇.
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Deno web compat is now on MDN! 🎉.
Web compatibility data for Deno is now available on @MozDevNet.
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Great tip! . Everything you need to know about <datalist> 👉🏽 Browser Compatibility 👇🏾
HTML tip:. Use the `<datalist>` element to create native HTML autocomplete.
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Is your website running slow? 🐌. Learn about performance from MDN’s curriculum. It covers core techniques like lazy loading, minimizing JavaScript, optimizing CSS, and reducing server response times to keep your app running fast. ⚡. Start right now 👇.
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DYK? You can contribute to MDN content via @github!. Join an amazing community of contributors all around the world who help us create content, fix bugs, review content changes, and add sample code.
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Ember tutorials are now available along with React and Vue! 👇👇.
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