MDN is more than just a resource. It's a community of developers, contributors, and learners passionate about web development. Contribute to, 📚 MDN documentation 🤝 Help other devs 💟 Localize content 📝 Review or write on MDN Start now 👇 developer.mozilla.org/en-US/commu...

➕ Meet abs() in CSS The abs() function returns the absolute value of a calculation, keeping numbers, lengths, or percentages always positive. Useful for safer layouts and predictable visuals. Learn more here ↓ developer.mozilla.org/en-US/docs/...

🦊 Firefox 147 is here! What's new? ✨ CSS Anchor Positioning enabled by default 🚀 WebGPU on all macOS with Apple Silicon 🧭 Navigation API for better SPA control 🎨 DevTools improvements for pseudo-elements & animations and more... Release notes 👇 developer.mozilla.org/en-US/docs/...

🆕 The URL Pattern API is Newly Available! Use it to match and extract parts of URLs, no need to reinvent routing logic. Supports literals, wildcards, named groups, and even regex constraints. Learn how it works 👇 developer.mozilla.org/en-US/docs/...

🦊 Firefox 147 is here! What's new? ✨ CSS Anchor Positioning enabled by default 🚀 WebGPU on all macOS with Apple Silicon 🧭 Navigation API for better SPA control 🎨 DevTools improvements for pseudo-elements & animations and more... Release notes 👇 developer.mozilla.org/en-US/docs/...

sign() is Newly Available on Baseline ➖➕ Unlike abs(), which returns a magnitude, sign() returns the direction of a value: -1, 1, 0, or -0. Useful when layout logic depends on whether a value is positive or negative. Learn more here 👇 developer.mozilla.org/en-US/docs/...

abs() in CSS? Yes, it's true! 🤯 The abs() function returns the absolute value of a calculation, keeping numbers, lengths, or percentages always positive. Useful for safer layouts and predictable visuals. Learn more here ↓ developer.mozilla.org/en-US/docs/...

Float16Array is Newly Available! 🆕 It represents an array of 16-bit floating point numbers in the platform byte order. If control over byte order is needed, use DataView instead. It is initialized to 0 unless initialization data is provided. Docs 👇 developer.mozilla.org/en-US/docs/...

No more padding hacks 🖼️ The aspect-ratio property lets you define a fixed width-to-height ratio for any element, making responsive design easier than ever. 🎥 Great for responsive media 🎴 Cleaner layouts w/o JS 📦 Works with grid, flexbox Read more ↓ developer.mozilla.org/en-US/docs/...

The 2025 Web Almanac by HTTP Archive has been officially released! 🚀 We would like to thank all of our contributors from around the globe who made this extensive report possible! Check out the full report here: almanac.httparchive.org

sign() is Newly Available on Baseline ➖➕ Unlike abs(), which returns a magnitude, sign() returns the direction of a value: -1, 1, 0, or -0. Useful when layout logic depends on whether a value is positive or negative. Learn more here 👇 developer.mozilla.org/en-US/docs/...

Fine-tune multilingual typography with text-autospace ✨ It lets you control spacing between CJK and Latin characters. > text-autospace: ideograph-alpha ideograph-numeric punctuation; Now available on Baseline 2025. 🎉 Learn more 👇 developer.mozilla.org/en-US/docs/...

Have you met <hue> ? 🎨 The CSS data type behind color angles. Used by hsl(), hwb(), lch(), and oklch(), <hue> represents a color’s position on the color wheel and automatically wraps around. Learn how it works 👇 developer.mozilla.org/en-US/docs/...

Need cross-thread synchronization without freezing the main thread? 🥶 Atomics.waitAsync() returns immediately and resolves when another thread calls Atomics.notify(). Perfect for coordinating workers with SharedArrayBuffer. Learn more 👇 developer.mozilla.org/en-US/docs/...

Firefox 146 brings WebDriver BiDi updates! 🤖 • setExtraHeaders for auto request header injection • Node context locating for iframes • Locale + timezone override improvements • Better network data collection • Reliable request IDs Release notes 👇 developer.mozilla.org/en-US/docs/...

➕ Meet abs() in CSS The abs() function returns the absolute value of a calculation, keeping numbers, lengths, or percentages always positive. Useful for safer layouts and predictable visuals. Learn more here ↓ developer.mozilla.org/en-US/docs/...

Need to convert a color between CSS formats? 🎨 The Color format converter lets you pick a color and instantly copy it as rgb(), hsl(), hex, and more - anywhere the <color> type is supported in CSS. Try it here 👇 developer.mozilla.org/en-US/docs/...

Firefox 146 ships improvements for CSS devs 🎨 • contrast-color() for WCAG-friendly contrast • display-p3-linear color space • text-decoration-inset • scope at-rule now on by default • -webkit-fill-available for better compat Release notes 👇 developer.mozilla.org/en-US/docs/...

MDN is built by Mozilla and a global community of contributors — writers, translators, engineers, educators. 🌍 Together we maintain 45K+ pages helping developers build the open web. Discover our mission & how to get involved 👇 developer.mozilla.org/en-US/about

Need cross-thread synchronization without freezing the main thread? 🥶 Atomics.waitAsync() returns immediately and resolves when another thread calls Atomics.notify(). Perfect for coordinating workers with SharedArrayBuffer. Learn more 👇 developer.mozilla.org/en-US/docs/...

📷 Ever wonder what’s really happening behind your web images? From pixels to formats to compression, you should use: - JPEG for details - PNG for transparency - WebP & AVIF for web-performance - SVG for resolution-independent graphics Read more 👇 developer.mozilla.org/en-US/blog/...

Happy New Year to the MDN community! 💟 Thank you for building the web with us. Writing docs, fixing bugs, reviewing PRs, and helping developers learn every day. Here’s to better standards, better tooling, and better documentation in the year ahead. 🥂

MDN is more than just a resource. It's a community of developers, contributors, and learners passionate about web development. Contribute to, 📚 MDN documentation 🤝 Help other devs 💟 Localize content 📝 Review or write on MDN Start now 👇 developer.mozilla.org/en-US/commu...

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 👇 developer.mozilla.org/en-US/docs/...

🦊 Firefox 146 is out! What's new: • Inspector: auto-hides unused CSS custom properties • contrast-color() + text-decoration-inset support • scope enabled by default • WeakMap/WeakSet now accept Symbol keys • WebDriver BiDi upgrades Release notes 👇 developer.mozilla.org/en-US/docs/...

MDN is more than just a resource. It's a community of developers, contributors, and learners passionate about web development. Contribute to, 📚 MDN documentation 🤝 Help other devs 💟 Localize content 📝 Review or write on MDN Start now 👇 developer.mozilla.org/en-US/commu...

Ever wish HTTP status codes were easier to remember? 🖼️ Check out this MDN cheatsheet that pairs each status code with an emoji to help you visualize what each one means, from 200 OK ✅ to 418 I’m a teapot 🫖 Check it out 👇

🆕 The URL Pattern API is Newly Available! Use it to match and extract parts of URLs, no need to reinvent routing logic. Supports literals, wildcards, named groups, and even regex constraints. Learn how it works 👇 developer.mozilla.org/en-US/docs/...

JavaScript's date object has been tricky for years, but that is changing. The NEW Temporal API brings, 🌍 Easily handle time zones 📆 Precise date math 🕒 Parse ISO strings without errors ⌛ Durations, date ranges, and more. Start experimenting 👇 developer.mozilla.org/en-US/docs/...

✨ One line of CSS. Smooth page transitions. No JavaScript. ``` @view-transition { navigation: auto; } ``` The 🆕 CSS View Transitions bring native animations to multi-page apps, no SPA setup needed! Explore now 👇 developer.mozilla.org/en-US/blog/...

Did you know? You can now build carousels with CSS! 🎠✨ They are responsive, accessible carousels and use only CSS. 🤯 🎯 Why CSS-only? ⋅ Simpler to maintain ⋅ Better performance ⋅ No external dependencies ⋅ Works out of the box Learn more 👇 developer.mozilla.org/en-US/docs/...

This is the web you know and build on. 🛠️ A great visual by HeyNina101 from SketechWorld, covering HTML & CSS to TCP & TLS - the core layers that keep everything running.

Let's learn about CSP (Content Security Policy) 🛡️ CSP, when set properly, ✅ Blocks malicious scripts from running on your site. ✅ Prevents data injection attacks. ✅ Reduces the risk of clickjacking and other web security threats. Learn more 👇 developer.mozilla.org/en-US/docs/...

Don’t fear the terminal, embrace it! 🫂 Get comfortable with the command line and learn, ✅ How to open your terminal ✅ Common commands like cd, ls, and mkdir ✅ How to create, move, and delete files and folders Get the cheat sheet! 👇 developer.mozilla.org/en-US/docs/...

You’ve learned how to write a function… now let’s make sure it works. 🫧 Practice real coding challenges with JavaScript functions – right in your browser, with interactive scrims from Scrimba. 🧠 Write, run, and debug your way to mastery developer.mozilla.org/en-US/docs/...

Tired of long-running scripts blocking the UI? The Web Workers API lets you run JS in the background, keeping your app responsive and smooth. ✅ Offload heavy tasks ✅ Keep the main thread free ✅ Great for data crunching, parsing, and more Read how 👇 developer.mozilla.org/en-US/docs/...

🦊 Firefox 146 is out! What's new: • Inspector: auto-hides unused CSS custom properties • contrast-color() + text-decoration-inset support • scope enabled by default • WeakMap/WeakSet now accept Symbol keys • WebDriver BiDi upgrades Release notes 👇 developer.mozilla.org/en-US/docs/...

🆕 The URL Pattern API is Newly Available! Use it to match and extract parts of URLs, no need to reinvent routing logic. Supports literals, wildcards, named groups, and even regex constraints. Learn how it works 👇 developer.mozilla.org/en-US/docs/...

<small> - It’s not just about font size! 🔠 It is meant to represent side comments, legal disclaimers, fine print, or less prominent text, not just make things smaller visually. 📜 Used for: Legal disclaimers Copyright notes A11y hints, etc Read more 👇 developer.mozilla.org/en-US/docs/...

Newly Available: CustomStateSet ✅ What is it? 🤔 It’s a new API that lets developers define and manage custom states on HTML elements, enabling fine-grained styling and behavior control using the :state() CSS pseudo-class. Start experimenting now 👇 developer.mozilla.org/en-US/docs/...

Firefox 146 brings WebDriver BiDi updates! 🤖 • setExtraHeaders for auto request header injection • Node context locating for iframes • Locale + timezone override improvements • Better network data collection • Reliable request IDs Release notes 👇 developer.mozilla.org/en-US/docs/...

✨ Meet Shrinivass, a Sr Full Stack Engineer from USA, contributing for over a year—improving docs like :has() and DOMContentLoaded. He says, “I contribute because it’s mentorship at scale. Each improvement helps thousands of devs.” Huge thanks! 🙌 developer.mozilla.org/en-US/commu...

Mastering layout = Mastering Flexbox Test your understanding with MDN’s hands-on Flexbox exercises. No setup needed, just code and see what happens, with interactive scrims ✨ 💡 Learn by solving developer.mozilla.org/en-US/docs/...

Firefox 146 ships improvements for CSS devs 🎨 • contrast-color() for WCAG-friendly contrast • display-p3-linear color space • text-decoration-inset • scope at-rule now on by default • -webkit-fill-available for better compat Release notes 👇 developer.mozilla.org/en-US/docs/...

Fine-tune multilingual typography with text-autospace ✨ It lets you control spacing between CJK and Latin characters. > text-autospace: ideograph-alpha ideograph-numeric punctuation; Now available on Baseline 2025. 🎉 Learn more 👇 developer.mozilla.org/en-US/docs/...

👩‍💻 Not a designer? No problem. If you're a developer who wants to build better-looking interfaces, this guide is made for you. It covers: ✅ Visual design principles ✅ Color, contrast, and typography ✅ Layout ✅ Visual hierarchy and balance Read now 👇 developer.mozilla.org/en-US/docs/...

🦊 Firefox 146 is out! What's new: • Inspector: auto-hides unused CSS custom properties • contrast-color() + text-decoration-inset support • scope enabled by default • WeakMap/WeakSet now accept Symbol keys • WebDriver BiDi upgrades Release notes 👇 developer.mozilla.org/en-US/docs/...

Ever wish HTTP status codes were easier to remember? 🖼️ Check out this MDN cheatsheet that pairs each status code with an emoji to help you visualize what each one means, from 200 OK ✅ to 418 I’m a teapot 🫖 Check it out 👇

Did you know about Strict Mode? 🤔 ✨ "use strict"; ✨ Strict Mode catches silent errors, making your code more predictable and easier to debug. It also improves performance and helps you write more secure JavaScript code. See how 👇 developer.mozilla.org/en-US/docs/...

📷 Ever wonder what’s really happening behind your web images? From pixels to formats to compression, you should use: - JPEG for details - PNG for transparency - WebP & AVIF for web-performance - SVG for resolution-independent graphics Read more 👇 developer.mozilla.org/en-US/blog/...