@developer.mozilla.org - MDN Web Docs

15 Jun 2026 11:00 +0000

🆕 Introducing the MDN MCP server! Bring MDN's docs and browser compat data straight into your AI agent or IDE for accurate, up-to-date answers about the web platform. No more outdated guesses from training data. Learn more 👇 developer.mozilla.org/en-US/blog/introducing-mdn-mcp-server/

18 May 2026 20:00 +0000

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 👇

18 May 2026 10:00 +0000

🦊 Firefox 150: web extensions can now use the Web Authentication API. Extensions can create and retrieve WebAuthn credentials for any domain covered by their host permissions. Read Now 👇 https://developer.mozilla.org/en-US/docs/Mozilla/Firefox/Releases/150

15 May 2026 03:00 +0000

🦊 New in Firefox 150: the revert-rule CSS keyword. Make a property behave as if the current rule didn't exist, letting a value from another matching rule take effect instead. Read Now 👇 https://developer.mozilla.org/en-US/docs/Mozilla/Firefox/Releases/150

14 May 2026 04:00 +0000

🦊 Firefox 150: light-dark() now accepts image values — not just colors. Use it with images and gradients to adapt visuals based on color scheme. background: light-dark(url(light.png), url(dark.png)); Read Now 👇 https://developer.mozilla.org/en-US/docs/Mozilla/Firefox/Releases/150

13 May 2026 06:00 +0000

🦊 Firefox 150 ships ariaNotify() on Document and Element. Queue text to be announced by a screen reader — a more ergonomic and reliable alternative to ARIA live regions. Read Now 👇 https://developer.mozilla.org/en-US/docs/Mozilla/Firefox/Releases/150

12 May 2026 20:00 +0000

🦊 Firefox 150: color-mix() now accepts more than two colors at once. Mix any number of colors in a single declaration — no more nesting multiple calls. Read Now 👇 https://developer.mozilla.org/en-US/docs/Mozilla/Firefox/Releases/150

12 May 2026 15:00 +0000

🦊 Firefox 150: is now supported. Lazy-loaded images use their calculated layout size to select from srcset — no more duplicating media queries in HTML. Read Now 👇 https://developer.mozilla.org/en-US/docs/Mozilla/Firefox/Releases/150

11 May 2026 20:00 +0000

Have you heard of CSS Subgrid? 🤔 A grid item can now pass its parent's grid lines to children, so nested elements align perfectly with the outer layout. No more hacky workarounds for aligned nested grids. Learn more 👇 https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_grid_layout/Subgrid

11 May 2026 10:00 +0000

🆕 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 👇 https://developer.mozilla.org/en-US/docs/Web/API/URL_Pattern_API

11 May 2026 10:00 +0000

Firefox 150 ships 7 media pseudo-classes: :buffering, :muted, :paused, :playing, :seeking, :stalled, :volume-locked. Style and elements based on their playback state. Read Now 👇 https://developer.mozilla.org/en-US/docs/Mozilla/Firefox/Releases/150

10 May 2026 16:00 +0000

Wait for all promises, even the failing ones 🔄 `Promise.allSettled()` waits for every promise to finish, success or failure. ⋅ Returns { status: 'fulfilled', value } or { status: 'rejected', reason } ⋅ Perfect for batch operations Learn more 👇 https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/allSettled

10 May 2026 10:00 +0000

✨ :only-child now matches elements with no parent! The :only-child selector has been updated — it can now match elements that have no parent at all, not just sole children. A subtle but useful spec alignment across all major browsers. Learn more 👇 https://developer.mozilla.org/en-US/docs/Web/CSS/:only-child

09 May 2026 13:30 +0000

09 May 2026 07:29 +0000

Build smooth scroll experiences with CSS scroll snap 📜 Snap scrollable containers to specific positions — carousels, galleries, and paginated views with zero JavaScript. Learn more 👇 https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_scroll_snap https://developer.mozilla.org/en-US/docs/Web/CSS/Guides/Scroll_snap

08 May 2026 19:00 +0000

📬 Check own properties safely with Object.hasOwn() A safer alternative to hasOwnProperty, works even on objects with a null prototype. Baseline since 2022 ✅ Learn more 👇 https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/hasOwn

08 May 2026 15:01 +0000

Create frosted glass effects in CSS 🪟 backdrop-filter applies visual effects to the content behind an element - blur, brightness, contrast, and more. backdrop-filter: blur(10px) brightness(0.9); No JavaScript. No canvas tricks. Learn more 👇 https://developer.mozilla.org/en-US/docs/Web/CSS/backdrop-filter

08 May 2026 03:00 +0000

The CSS next-sibling combinator (+) selects an element only when it immediately follows another, same parent, no elements between them. img + p { font-weight: bold; } Learn more 👇 https://developer.mozilla.org/en-US/docs/Web/CSS/Reference/Selectors/Next-sibling_combinator