Major versions of Firefox now land every two weeks, so Firefox 155 dropped today with web platform features including:
🎉 Fully typed CSS attr()
🎉 CSS progress()
🎉 Promise.allKeyed() and allSettledKeyed()
🎉 Lots of new WebTransport stuff
…And more!
developer.mozilla.org/en-US/docs/Moz…
Firefox 154 landed today, and brings with it some great web platform features:
🎉 CSS text-box
🎉 CSS sibling-index() and sibling-count()
🎉 JS Iterator methods like chunks, window, includes, & join
🎉 HTTP No-Vary-Search
…And more! developer.mozilla.org/en-US/docs/Moz…
The Web Serial API landed in Firefox 151, allowing you to connect directly to microcontrollers, dev boards, 3D printers, power meters, and other serial-connected hardware from the web. Here's how it works:
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 👇
🦊 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 👇
developer.mozilla.org/en-US/docs/Moz…
🦊 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 👇
developer.mozilla.org/en-US/docs/Moz…
🦊 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 👇
developer.mozilla.org/en-US/docs/Moz…
🦊 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 👇
developer.mozilla.org/en-US/docs/Moz…
🦊 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 👇
developer.mozilla.org/en-US/docs/Moz…
🦊 Firefox 150: <img sizes="auto"> is now supported.
Lazy-loaded images use their calculated layout size to select from srcset — no more duplicating media queries in HTML.
Read Now 👇
developer.mozilla.org/en-US/docs/Moz…
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 👇
developer.mozilla.org/en-US/docs/Web…
Firefox 150 ships 7 media pseudo-classes: :buffering, :muted, :paused, :playing, :seeking, :stalled, :volume-locked.
Style <audio> and <video> elements based on their playback state.
Read Now 👇
developer.mozilla.org/en-US/docs/Moz…
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