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指定座標のテキスト位置を取得するメソッド。 どこで使えばいいのかわかりませんが、クリックしたところに改行を挿入するサンプルが置いてあります。 こういう英語の情報はほとんど流れてこなかったのですが、自動翻訳機能によって流れてくるようになりましたね。 MDN 公式のアカウントでしょうか？

Aujourd'hui c'est le premier mercredi du mois, une occasion de participer #MDN Mercredi Docs https://www. meetup.com/fr-fr/firefox-… @MozDevNet @MDNfr @mozilla_fr

🆕 Document.caretPositionFromPoint() is Newly Available! Give it an (x, y) coordinate and get back the exact DOM node and character offset. Perfect for click-to-edit interfaces. Check it out 👇 developer.mozilla.org/en-US/docs/Web…

Creating a resolvable Promise just got cleaner 🧹 `Promise.withResolvers()` returns { promise, resolve, reject } No more wrapping logic inside the constructor. Learn more 👇 developer.mozilla.org/en-US/docs/Web…

CSS nesting is now Baseline 🎉 Write nested selectors directly in CSS — just like Sass, but natively. .card { color: black; &:hover { color: blue; } .title { font-weight: bold; } } No preprocessor needed. Learn more 👇 developer.mozilla.org/en-US/docs/Web…

CSS subgrid solves the hardest grid alignment problems 🏗️ Child elements can participate in the parent grid — aligning across components without hacks. grid-template-columns: subgrid; grid-template-rows: subgrid; Baseline 2023 ✅ Learn more 👇 developer.mozilla.org/en-US/docs/Web…

Access array elements from the end with .at() 🎯 arr.at(-1) returns the last element — clean, readable, works on all array-like structures. const last = [1, 2, 3].at(-1); // 3 No more arr[arr.length - 1] everywhere. Learn more 👇 developer.mozilla.org/en-US/docs/Web…

Style native form controls with just one CSS property 🎨 accent-color sets the tint color for checkboxes, radio buttons, range inputs, and progress bars. No custom checkbox hacks. Just CSS. Learn more 👇 developer.mozilla.org/en-US/docs/Web…

Compress and decompress data in the browser natively 📦 The Compression Streams API brings gzip and deflate to the web, no libraries needed. ⋅ Works with ReadableStream and WritableStream ⋅ Compresses arbitrary data client-side Learn more 👇 developer.mozilla.org/en-US/docs/Web…

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

Hold object references without preventing garbage collection 🗑️ `WeakRef` lets you reference an object while allowing it to be GC’d if nothing else holds a strong reference. Use for caches, and pair with FinalizationRegistry. Learn more 👇 developer.mozilla.org/en-US/docs/Web…

Measure your own code performance precisely ⏱️ `performance.mark()` and `performance.measure()` let you instrument JavaScript with high-precision timings. Learn more 👇 developer.mozilla.org/en-US/docs/Web…

Creating a resolvable Promise just got cleaner 🧹 `Promise.withResolvers()` returns { promise, resolve, reject } No more wrapping logic inside the constructor. Learn more 👇 developer.mozilla.org/en-US/docs/Web…

Run non-critical work without blocking the UI 💤 `requestIdleCallback()` schedules tasks during browser idle time. ⚠️ Limited Availability ⋅ Runs only when the main thread is free ⋅ Great for analytics, prefetching, and cleanup Learn more 👇 developer.mozilla.org/en-US/docs/Web…

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 👇 developer.mozilla.org/en-US/docs/Web…

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 👇 developer.mozilla.org/en-US/docs/Web…

Stop scroll chaining with overscroll-behavior 🛑 Prevent modals and sidebars from accidentally scrolling the page behind them. ⋅ Works on any scrollable element ⋅ Also controls the bounce effect on mobile Learn more 👇 developer.mozilla.org/en-US/docs/Web…

Access characters from the end of a string with .at() ✨ str.at(-1) gets the last character, no more str[str.length - 1] gymnastics. Works on strings, arrays, and typed arrays. Learn more 👇 developer.mozilla.org/en-US/docs/Web…

🆕 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 👇 developer.mozilla.org/en-US/docs/Web…

📬 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 👇 developer.mozilla.org/en-US/docs/Web…