MDN Web Docs (@MozDevNet)

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MDN Web Docs@MozDevNet · Jun 23

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 👇

MozDevNet's tweet image. 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 👇

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MDN Web Docs@MozDevNet · 5 h

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/Web…

MozDevNet's tweet card. The aspect-ratio CSS property allows you to define the desired width-to-height ratio of an element's box. This means that even if the parent container or viewport size changes, the browser will...

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MDN Web Docs@MozDevNet · Jul 21

Newly Available starting Firefox 140 ✅ 🍪 CookieStore API offers a modern, promise-based way to read, write, update, and delete cookies, all without parsing strings manually. It brings, ✅ Async operations ✅ Structured data ✅ Service worker support 👇 developer.mozilla.org/en-US/docs/Web…

MozDevNet's tweet card. The CookieStore interface of the Cookie Store API provides methods for getting and setting cookies asynchronously from either a page or a service worker.

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MDN Web Docs@MozDevNet · Jul 18

Building extensions with @mozamo? Try tabGroups API 📑 The tabGroups API lets you interact with tab groups, giving users better control over their open tabs through your extension. What's possible? - Tab managers - Declutter browsers - Smarter workflows developer.mozilla.org/en-US/docs/Moz…

MozDevNet's tweet card. This API enables extensions to modify and rearrange tab groups.

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MDN Web Docs@MozDevNet · Jul 17

Working with <dialog> elements? 🤔 Don't use .close(), it ends the dialog immediately. Use HTMLDialogElement.requestClose(), it fires a close event first, giving your app a chance to intercept it, useful for confirmation or animations. Try now 👇 developer.mozilla.org/en-US/docs/Web…

MozDevNet's tweet card. The requestClose() method of the HTMLDialogElement interface requests to close the . An optional string may be passed as an argument, updating the returnValue of the dialog.

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MDN Web Docs@MozDevNet · Jul 16

🔍 Want to highlight text without touching the DOM? The CSS.highlights API lets you apply custom visual highlights to text ranges using JavaScript + CSS. ❇️ Great for annotations, search results, or reading aids. Check it out 👇 developer.mozilla.org/en-US/docs/Web…

MozDevNet's tweet card. The static, read-only highlights property of the CSS interface provides access to the HighlightRegistry used to style arbitrary text ranges using the CSS Custom Highlight API.

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MDN Web Docs@MozDevNet · Jul 15

✅ Newly Available: CookieChangeEvent It lets you respond to cookie changes as they happen, using modern event-driven logic in your app or service worker. The event is fired when cookies are added, changed, or deleted. Try now 👇 developer.mozilla.org/en-US/docs/Web…

MozDevNet's tweet card. The CookieChangeEvent() constructor creates a new CookieChangeEvent object which is the event type of the change event fired at a CookieStore when any cookie changes occur. This constructor is called...

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MDN Web Docs@MozDevNet · Jul 14

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 👇 developer.mozilla.org/en-US/blog/htm…

MozDevNet's tweet card. The 'name' attribute of the HTML details element is gaining more support across browsers. Learn how this feature allows creating exclusive accordions without scripting widgets from scratch.

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MDN Web Docs@MozDevNet · Jul 10

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/Web…

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MDN Web Docs Retweeted

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Firefox Beta@firefoxbeta · Jul 9

Firefox 141 Beta 8 is out with 14 bug fixes bugzilla.mozilla.org/buglist.cgi?bu…

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MDN Web Docs@MozDevNet · Jul 8

📚 The MDN Curriculum is your guide to mastering front-end development! Covering all the fundamentals, it links to the best resources, including those from our learning partner, @scrimba. 🤝 Explore now 👇 developer.mozilla.org/en-US/curricul…

MozDevNet's tweet card. The MDN Curriculum provides a structured guide to the essential skills and practices for being a successful front-end developer, along with recommended learning resources.

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Firefox Nightly 🔥@FirefoxNightly · Jul 6

The Text Fragments creation UI was just activated in Firefox Nightly allowing you to share/reference a link anchor to any text snippet in a page bugzilla.mozilla.org/1970641

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MDN Web Docs@MozDevNet · Jul 7

In our last community call, @YashRaj49744398 gave amazing demos on what's new in CSS! 🎨 In this video, he goes through the new view-transition that can help you gain full visual control over what changes, and without JavaScript elements. Read more 👇 developer.mozilla.org/en-US/docs/Web…

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MDN Web Docs@MozDevNet · Jul 4

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/Web…

MozDevNet's tweet card. Compression Dictionary Transport is a way of using a shared compression dictionary to dramatically reduce the transport size of HTTP responses.

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MDN Web Docs@MozDevNet · Jul 3

The MDN Content Team has crafted the latest Firefox 140 Developer Release Notes! 🔥🦊 We've got: CSS Custom Highlight API supported Removed some UA styles for <h1> elements fetchpriority attribute is now supported for SVG ...and more! What's new 👇 developer.mozilla.org/en-US/docs/Moz…

MozDevNet's tweet card. This article provides information about the changes in Firefox 140 that affect developers. Firefox 140 was released on June 24, 2025.

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MDN Web Docs@MozDevNet · Jul 2

Are you still not using JavaScript Sets? Discover ↓ ✨ set.union() ✨ set.intersection() ✨ set.difference() See how sets might make your data efficient. Dive in! 👇 developer.mozilla.org/en-US/blog/jav…

MozDevNet's tweet card. New JavaScript Set methods are landing across browsers. Learn about sets, how you can use these methods to compare different sets, create new sets with specific properties, and more.

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MDN Web Docs@MozDevNet · Jul 1

Newly Available starting Firefox 140 ✅ 🍪 CookieStore API offers a modern, promise-based way to read, write, update, and delete cookies, all without parsing strings manually. It brings, ✅ Async operations ✅ Structured data ✅ Service worker support 👇 developer.mozilla.org/en-US/docs/Web…

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MDN Web Docs@MozDevNet · Jun 30

Only one day left! ☝️ Calling all frontend developers, designers, and CSS lovers! 🎨 The annual State of CSS survey is closing soon, and your input helps shape the future of the web platform. Whether you're new to CSS or not, your voice matters! 🙌 survey.devographics.com/en-US/survey/s…

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MDN Web Docs@MozDevNet · Jun 30

日付を扱いやすくなった #Javascript のTemporal API 仕様

MMDN Web Docs@MozDevNet · Jun 30

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/Web…

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MDN Web Docs@MozDevNet · Jun 30

The dark days are over! *In some timezones, and not on a leap year.

MMDN Web Docs@MozDevNet · Jun 30

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/Web…

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MDN Web Docs@MozDevNet · Jun 30

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/Web…

MozDevNet's tweet card. The Temporal object enables date and time management in various scenarios, including built-in time zone and calendar representation, wall-clock time conversions, arithmetics, formatting, and more. It...

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