サクサク読めて、アプリ限定の機能も多数！
トップへ戻る
ドラクエ3
jakearchibald.com
Me, Surma, and Jason were hacking on a thing, and discovered that garbage collection within a function doesn't quite work how we expected. function demo() { const bigArrayBuffer = new ArrayBuffer(100_000_000); const id = setTimeout(() => { console.log(bigArrayBuffer.byteLength); }, 1000); return () => clearTimeout(id); } globalThis.cancelDemo = demo(); With the above, bigArrayBuffer is leaked fore
Attributes and properties are fundamentally different things. You can have an attribute and property of the same name set to different values. For example: <div foo="bar">…</div> <script> const div = document.querySelector('div[foo=bar]'); console.log(div.getAttribute('foo')); // 'bar' console.log(div.foo); // undefined div.foo = 'hello world'; console.log(div.getAttribute('foo')); // 'bar' consol
This post assumes some knowledge of view transitions. If you're looking for a from-scratch intro to the feature, see this article. When folks ask me for help with view transition animations that "don't quite look right", it's usually because the content changes aspect ratio. Here's how to handle it: Unintentional aspect ratio changes It's pretty common for these aspect ratio changes to be unintent
Let's talk about />: <input type="text" /> <br /> <img src="…" />You'll see this syntax on my blog because it's what Prettier does, and I really like Prettier. However, I don't think /> is a good thing. First up: The facts Enter XHTML Back in the late 90s and early 2000s, the W3C had a real thing for XML, and thought that it should replace HTML syntax. There were good reasons for this. At the time
By default, an <img> takes up zero space until the browser loads enough of the image to know its dimensions: When you run the demo, you'll see the <figcaption> immediately. Then, after a few seconds, this paragraph and subsequent page content shifts downwards to make room for the image. This makes the user experience massively frustrating, as content moves out from under the user's eyes/finger/poi
CORS (Cross-Origin Resource Sharing) is hard. It's hard because it's part of how browsers fetch stuff, and that's a set of behaviours that started with the very first web browser over thirty years ago. Since then, it's been a constant source of development; adding features, improving defaults, and papering over past mistakes without breaking too much of the web. Anyway, I figured I'd write down pr
`export default thing` is different to `export { thing as default }` Dominic Elm DM'd me on Twitter to ask me questions about circular dependencies, and, well, I didn't know the answer. After some testing, discussion, and *ahem* chatting to the V8 team, we figured it out, but I learned something new about JavaScript along the way. I'm going to leave the circular dependency stuff to the end of the
Right now, when you go to copilot.github.com you're greeted with this example: async function isPositive(text) { const response = await fetch(`http://text-processing.com/api/sentiment/`, { method: 'POST', body: `text=${text}`, headers: { 'Content-Type': 'application/x-www-form-urlencoded', }, }); const json = await response.json(); return json.label === 'pos'; } This is bad and might result in sec
// Convert some numbers into human-readable strings: import { toReadableNumber } from 'some-library'; const readableNumbers = someNumbers.map(toReadableNumber);
Back in ancient July I released a video that dug into how lossy and lossless image compression works and how to apply that knowledge to compress a set of different images for the web. Well, that's already out of date because AVIF has arrived. Brilliant. AVIF is a new image format derived from the keyframes of AV1 video. It's a royalty-free format, and it's already supported in Chrome 85 on desktop
Different versions of your site can be running at the same time It's pretty easy for a user to be running an old version of your site. Not only that, but a user could be running many different versions of your site at the same time, in different tabs, and that's kinda terrifying. For instance: A user opens your site. You deploy an update. The user opens one of your links in a new tab. You deploy a
async function showImageSize(url) { const blob = await fetch(url).then((r) => r.blob()); const img = await createImageBitmap(blob); updateUISomehow(img.width, img.height); } btn1.onclick = () => showImageSize(url1); btn2.onclick = () => showImageSize(url2); This has a race condition. If the user clicks btn1, then btn2, it's possible that the result for url2 will arrive before url1. This isn't the
Last month we had a service worker meeting at the W3C TPAC conference in Fukuoka. For the first time in a few years, we focused on potential new features and behaviours. Here's a summary: Resurrection finally killed If you unregister a service worker registration, it's removed from the list of registrations, but it continues to control existing pages. This means it doesn't break any ongoing fetche
I was trying to make my predictions for the new Formula One season by studying the aerodynamics of the cars, their cornering speeds, their ability to run with different amounts of fuel. Then it hit me: I have no idea what I'm doing. So, I'm going to make my predictions the only way I know how: By comparing the performance of their websites. That'll work right? If anything, it'll be interesting to
I'm looking for feedback on this API. It isn't yet supported in any standard or browser. In the very early days of service workers (while they were still named "navigation controllers") we had the idea of a declarative router. This provided a high-level API to define the behaviour of particular routes, so the service worker wouldn't need to be started. We dropped the idea because we didn't want to
I accidentally discovered a huge browser bug a few months ago and I'm pretty excited about it. Security engineers always seem like the "cool kids" to me, so I'm hoping that now I can be part of the club, and y'know, get into the special parties or whatever. I've noticed that a lot of these security disclosure things are only available as PDFs. Personally, I prefer the web, but if you're a SecOps P
A few days ago there was a lot of chatter about a 'keylogger' built in CSS. Some folks called for browsers to 'fix' it. Some folks dug a bit deeper and saw that it only affected sites built in React-like frameworks, and pointed the finger at React. But the real problem is thinking that third party content is 'safe'. Third party images If I include the above, I'm trusting example.com. They may betr
On Twitter, Allen Wirfs-Brock asked folks if they knew what Array.isArray(obj) did, and the results suggested… no they don't. For what it's worth, I also got the answer wrong. Type-checking arrays Let's say we wanted to do something specific if obj is an array. JSON.stringify is an example of this, it outputs arrays differently to other objects. We could do:
When writing async functions, there are differences between await vs return vs return await, and picking the right one is important. Let's start with this async function: async function waitAndMaybeReject() { // Wait one second await new Promise((r) => setTimeout(r, 1000)); // Toss a coin const isHeads = Boolean(Math.round(Math.random())); if (isHeads) return 'yay'; throw Error('Boo!'); } This ret
Netflix functions without client-side React, and it's a good thing A few days ago Netflix tweeted that they'd removed client-side React.js from their landing page and they saw a 50% performance improvement. It caused a bit of a stir. This shouldn't be a surprise The following: Download HTML & CSS in parallel. Wait for CSS to finish downloading & execute it. Render, and continue rendering as HTML d
Phwoar I love a good sciency-sounding title. SVG can be slow When transforming an SVG image, browsers try to render on every frame to keep the image as sharp as possible. Unfortunately SVG rendering can be slow, especially for non-trivial images. Here's a demo, press "Scale SVG". Devtools timeline for SVG animation Sure, this is a pretty complex SVG, but we're 10x over our frame budget on some fra
"HTTP/2 push will solve that" is something I've heard a lot when it comes to page load performance problems, but I didn't know much about it, so I decided to dig in. HTTP/2 push is more complicated and low-level than I initially thought, but what really caught me off-guard is how inconsistent it is between browsers – I'd assumed it was a done deal & totally ready for production. This isn't an "HTT
ES modules are now available in browsers! They're in… Safari 10.1. Chrome 61. Firefox 60. Edge 16. <script type="module"> import { addTextToBody } from './utils.mjs'; addTextToBody('Modules are pretty cool.'); </script> // utils.mjs export function addTextToBody(text) { const div = document.createElement('div'); div.textContent = text; document.body.appendChild(div); } Live demo. All you need is t
Streaming fetches are supported in Chrome, Edge, and Safari, and they look a little like this: async function getResponseSize(url) { const response = await fetch(url); const reader = response.body.getReader(); let total = 0; while (true) { const { done, value } = await reader.read(); if (done) return total; total += value.length; } } This code is pretty readable thanks to async functions (here's a
There's a proposal to add a new <h> element to the HTML spec. It solves a fairly common use-case. Take this HTML snippet: <div class="promo"> <h2>Do you find the "plot" a distraction in movies?</h2> <p>If so, you should check out "John Wick" - satisfaction guaranteed!</p> </div> This could be a web component, or a simple include. The problem is, by using <h2>, we've assumed the 'parent' heading is
I've been working on the web since I was a small child all the way through to the haggard old man I am to day. However, the web still continues to surprise me. Turns out, mouse events don't fire when the pointer is over disabled form elements, except in Firefox. Serious? Serious. Give it a go. Move the mouse from the blue area below into the disabled button: It's not like the disabled button eleme
Posted 06 December 2016 - Seems I'm finding everything "fun" right now A few weeks ago I was at Heathrow airport getting a bit of work done before a flight, and I noticed something odd about the performance of GitHub: It was quicker to open links in a new window than simply click them. Here's a video I took at the time: GitHub link click vs new tab Here I click a link, then paste the same link int
One of the great things about SVG is you can use media queries to add responsiveness to images: <svg width="100" height="100" xmlns="http://www.w3.org/2000/svg"> <style> circle { fill: green; } @media (min-width: 100px) { circle { fill: blue; } } </style> <circle cx="50" cy="50" r="50"/> </svg> <img src="circle.svg" width="50" height="50" /> <img src="circle.svg" width="100" height="100" /> <ifram
Posted 04 August 2016 - using my year's quota of bullets in one post On July 28th-29th we met up in the Mozilla offices in Toronto to discuss the core service worker spec. I'll try and cover the headlines here. Before I get stuck in to the meaty bits of the meeting, our intent here is to do what's best for developers and the future of the web, so if you disagree with any of this, please make your
次のページ
このページを最初にブックマークしてみませんか？
『Blog - JakeArchibald.com』の新着エントリーを見る
j次のブックマーク
k前のブックマーク
lあとで読む
eコメント一覧を開く
oページを開く
