Web における Beacon の変遷 (sendBeacon(), fetch() keepalive, fetchLater()) | blog.jxck.io
Intro ページを閉じる際に何かしらの情報をサーバで収集したいケースがある。 これを Beacon の送信(Beaconing)と呼び、ブラウザではページ表示中に収集したパフォーマンス統計の収集や、広告タグによるトラッキングなどに用いられる。 しかし、「ページが閉じる直前に、サーバにリクエストを送信する」を確実に実行するのは実は難しく、これを標準技術で実現する過程で、複数の API が生まれるに至った。 各 API の策定経緯と、挙動の違いについて解説していく。 <img> での送信 最もプリミティブな Beacon の送信は、<img> を用いたものだった。 window.addEventListener("unload", () => { const beaconImage = new Image(1, 1); beaconImage.src = "https://telemetry
How To Improve INP: Yield Patterns
In the following, we’ll go over different patterns we can use to yield to the main thread to improve the Interaction-to-Next-Paint (INP). Knowing how to improve INP is more important than ever, as it’s a metric reflecting User Experience (UX) and has recently been added to the Core Web Vitals (CWVs) – which are used by Google’s search ranking. We’ll take a look at which part of INP we’re targettin
Misconceptions about view transitions | Blog | Chrome for Developers
::view-transition └─ ::view-transition-group(root) | └─ ::view-transition-image-pair(root) | ├─ ::view-transition-old(root) | └─ ::view-transition-new(root) └─ ::view-transition-group(box) └─ ::view-transition-image-pair(box) ├─ ::view-transition-old(box) └─ ::view-transition-new(box) While this tree contains multiple snapshot pairs only a single view transition is run. Currently, Chrome is limite
WebPerf Snippets – Nextra
WebPerf Snippets A curated list of snippets to get Web Performance metrics to use in the browser console or as snippets on Chrome DevTools (opens in a new tab). How to use Requirements All the snippets are tested in Google Chrome (opens in a new tab) browser, so use this browser to garantize the correct funcionality. Run in the browser console You can copy any snippet and then paste in the browser
CSS Custom Highlight API - Web APIs | MDN
The CSS Custom Highlight API provides a mechanism for styling arbitrary text ranges on a document by using JavaScript to create the ranges, and CSS to style them. Styling text ranges on a webpage can be very useful. For example, text editing web apps highlight spelling or grammar errors, and code editors highlight syntax errors. The CSS Custom Highlight API extends the concept of other highlight p
Service Worker Static Routing API Origin Trial | Blog | Chrome for Developers
Service workers are a powerful tool for allowing websites to work offline and create specialized caching rules for themselves. A service worker fetch handler sees every request from a page it controls, and can decide if it wants to serve a response to it from the service worker cache, or even rewrite the URL to fetch a different response entirely—for instance, based on local user preferences. Howe
Get All That Network Activity Under Control with Priority Hints
Get All That Network Activity Under Control with Priority Hints The browser is very good at prioritizing resources requests on its own. But it's not always great. Priority hints makes it easy to provide explicit instructions as to how and in what network activity occurs. Open up the browser's network tab and you'll see a lot of activity. Assets are being downloaded, information's being submitted,
Introducing the scheduler.yield origin trial | Blog | Chrome for Developers
Building websites that respond quickly to user input has been one of the most challenging aspects of web performance—one that the Chrome Team has been working hard to help web developers meet. Just this year, it was announced that the Interaction to Next Paint (INP) metric would graduate from experimental to pending status. It is now poised to replace First Input Delay (FID) as a Core Web Vital in
Deprecating the unload event | Web Platform | Chrome for Developers
All sites deprecation timeline. Note that we also offer a menu of opt-out options in case this deprecation timeline doesn't provide sufficient time to migrate away from unload. Our goal is to use this soft deprecation to inform the timeline for the last phase (hard deprecation of unload) in which these opt-outs will be removed or reduced. Timeline of the unload deprecation. Background unload was d
AbortSignal.any(), AbortSignal.timeout(), そして addEventListener() の Signal | blog.jxck.io
Intro 最近 AbortSignal.any() が提案され、急速に実装が進んでいる。 すでに定義されている AbortSignal.timeout() や addEventListener() への Signal なども含め、非同期処理の中断を実装する際の API はかなり整備されてきた。 これら API のモチベーションと設計を中心にまとめる。 Abort 後のリソース解放 AbortSignal によって、非同期処理のキャンセルが可能になった。例として、Server 上での Fetch のタイムアウトの例を考えよう。 app.get("/entries", async (req, res) => { const perRequestController = new AbortController() const perRequestSignal = perRequestContr
The origin private file system | Articles | web.dev
Motivation When you think of files on your computer, you probably think about a file hierarchy: files organized in folders that you can explore with your operating system's file explorer. For example, on Windows, for a user called Tom, their To Do list might live in C:\Users\Tom\Documents\ToDo.txt. In this example, ToDo.txt is the filename, and Users, Tom, and Documents are folder names. `C:` on W
The User Activation API
As a web developer, you’ve probably noticed that certain APIs only work if an end-user clicks or taps on an HTML element. For example, if you try to run the following code in Safari’s Web Inspector, it will result in an error: await navigator.share({ text: "hi" }); NotAllowedError: The request is not allowed by the user agent or the platform in the current context, possibly because the user denied
Smooth transitions with the View Transition API | View Transitions | Chrome for Developers
The View Transition API gives you the power to create seamless visual transitions between different views on your website. This creates a more visually engaging user experience for users as they navigate your site, regardless of whether it's built as a multi-page application (MPA) or a single-page application (SPA). Typical situations where you would use view transitions include: A thumbnail image
Introducing WebContainers: Run Node.js natively in your browser
Introducing WebContainers: Run Node.js natively in your browser Update: Since the publication of this blog post in May 2021, WebContainers became stable and available on Firefox. Most importantly, we released the WebContainers API for you all to enjoy! You can even self-host the API with StackBlitz Enterprise. Get in touch to learn more. A few years ago we realized that the web was heading towards
WebCodecs と WebTransport でビデオチャット | blog.jxck.io
Intro ブラウザの持つ Video/Audio コーデック実装へアクセスする API として WebCodecs の仕様策定と実装が進んでいる。 これにより、映像や音声の変換などといったユースケースへの応用も可能だ。 本来なら WebCodecs 単体の API について解説するところだが、筆者がこの API を待っていた理由であるところの「WebRTC の代替」としての WebCodecs/WebTransport の応用に注目し、背景も踏まえて解説する。 WebRTC WebRTC は UDP 上に DTLS で交換した鍵を用いて、RTP を SRTP で流し、そのシグナリングに SDP を、ホールパンチに ICE(STUN/TURN) を用いることで、P2P ビデオチャットといったユースケースを可能にした API だ。 しかし、最初から「P2P ビデオチャット」というユースケース
Layered APIs と High Level API の標準化指針 | blog.jxck.io
Intro Extensible Web Manifest 以降、標準化作業は Low Level API にフォーカスし、一定の成果が出ている。 そこで、これらをベースとし、よりアプリレイヤの需要を満たすための High Level API をどう標準化するか、という点について指針が提案された。 基本は、Low Level API を元に Polyfill を作り、そこからのフィードバックにより策定を進めるという方針だ。 合わせて ES Modules の Import を用いて、polyfill とネイティブ実装をスムーズに切り替える拡張が提案されている。 本記事では Layered APIs (LAPIs) と呼ばれる、この一連の枠組みについて解説する。 また、同等の話を 東京 Node 学園 #tng30 で行った資料は以下である。 Web over Layered APIs St
Sputnik
What is Sputnik? Sputnik is a JavaScript 3 conformance test suite. The purpose of the test suite is to determine how well a JavaScript implementation adheres to the ECMA-262 specification, 3rd edition. It contains over 5000 tests that touch all aspects of the JavaScript language. What is this site? This site allows you to run the sputnik tests and to compare the most popular browsers' test results
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Translator and Language Detector APIs - Web APIs | MDN
Scrollend, a new JavaScript event | Blog | Chrome for Developers
http://kangax.github.io/es5-compat-table/