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What's next for JavaScript? A REMOTE CONF TO FIGHT COVID-19 July 13-17, 2020 👾 A new take on the fully-remote conference. 📅 12 amazing speakers spread across 5 days. 🤝 100% of ticket proceeds donated to combat the COVID-19 pandemic: Doctors Without Borders and several other charities nominated by our speakers.
Annex B について JavaScript の言語仕様には Annex B という項目があります。ここには Web 互換性のために残されているレガシーな機能の仕様について記述してあり、新たに ECMAScript のコードを書く際にこれらの機能を使用したり、その存在を前提にしたりしてはいけないと明記されています。 String#big などの今となっては全く実用性のないメソッドや、escape, unescape 函数、もともと IE の独自実装だった String#substr などについて記述されています。 ブラウザではこれらの機能を取り除くことが出来ないので残念ながら扱うことが出来ます。また Chrome の JavaScript エンジンである V8 を使っている Node.js や Deno でも Web 互換性を重視していることもあって扱うことが出来ます。 一方で Web
JSer.info #493 - ECMAScript 2020がEcma internationalの119th General Assemblyで承認され、正式にリリースされました。 Ecma latest news Release ES2020 · tc39/ecma262 proposals/finished-proposals.md at master · tc39/proposals ECMAScript 2020では次のような変更が含まれています。 for-in mechanics - for...inやObject.keysの順番が仕様で定義された export * as ns from "mod" - 構文の追加 String.prototype.matchAll - マッチしたすべての文字列をイテレータで返す globalThis - ブラウザのwindow、Node.
はじめに JavaScript: Everything From ES2016 to ES2019のを読み、本稿はES2018で導入された機能についてわかったことを自分なりにまとめたものになります。 レスト構文とスプレッド構文(Rest/Spread)をオブジェクトにも使用可能 ES2015では、配列にスプレッド構文を使用することができました。 const name = ["taro", "ichiro", "hanako"]; const spread_name = [...name, "jiro"]; console.log(spread_name); //["taro", "ichiro", "hanako", "jiro"]
This is a tool that converts CommonJS modules into tree-shakeable ES Modules. This allows you to not only bundle CommonJS modules for the browser, but also makes it possible for you to bundle them in modern tools such as Rollup. It can also be used as a tool for migrating a CommonJS-based codebase to one based on ES-modules via a simple CLI. cjstoesm can be used from the Command Line, as a JavaScr
Endo is a JavaScript platform under development for secure communication among objects within one process and distributed between mutually suspicious machines. The foundation of Endo is Hardened JavaScript as implemented by ses, a tamper-proof JavaScript environment that allows safe execution of arbitrary programs in Compartments. Most JavaScript libraries built for Node.js, either in CommonJS or
TC39 の 86 回目のミーティングが 10/25 ~ 10/28 に開催されました。 このミーティングで議題に上がった提案と、そのステージの移動について紹介します。 agendas/10.md at master · tc39/agendas Oct 2021 · Issue #77 · babel/proposals for Stage 4 Error Cause Stage 4 になりました。ECMAScript 2022 に入ります Error Cause は、Error コンストラクタの第 2 引数に cause という値で原因となったエラーを渡すことができるようにする提案です。 キャッチする側では、error.cause で、そのエラーを取得できます。 例を示します。 doUploadJob 関数は fetch を実行して失敗したときに新しいエラーをスローします。そのエラーの
Show navigation Generally, references to objects are strongly held in JavaScript, meaning that as long you have a reference to the object, it won’t be garbage-collected. const ref = { x: 42, y: 51 }; // As long as you have access to `ref` (or any other reference to the // same object), the object won’t be garbage-collected.Currently, WeakMaps and WeakSets are the only way to kind-of-weakly referen
reg is a package manager for native ES Modules. It's built to enable dependency management for Universal JavaScript (JavaScript that can run in the Browser and in Node.js w/o a compiler). This library is highly experimental and still likely to break without notice. DO NOT USE THIS IN PRODUCTION. Supporting Universal JavaScript is quite difficult as the Browser's module system has a very unique set
Dan Fabulich is a Principal Engineer at Redfin. (We’re hiring!) In Node 14, there are now two kinds of scripts: there are old-style CommonJS (CJS) scripts and new-style ESM scripts (aka MJS). CJS scripts use require() and module.exports; ESM scripts use import and export. ESM and CJS are completely different animals. Superficially, ESM looks very similar to CJS, but their implementations couldn’t
This release doesn't contain any deliberately-breaking changes. However, it contains a very complex new feature and while all of esbuild's tests pass, I would not be surprised if an important edge case turns out to be broken. So I'm releasing this as a breaking change release to avoid causing any trouble. As usual, make sure to test your code when you upgrade. Implement the JavaScript decorators p
In this blog post, we examine the ECMAScript proposal “JSON modules” (by Sven Sauleau, Daniel Ehrenberg, Myles Borins, and Dan Clark). It lets us import JSON data as if it were an ECMAScript module. Why would we want to import JSON like a module? # Various bundlers (such as webpack) have allowed us to import JSON data as if it were an ECMAScript module for a long time. JSON modules turn this into
Ecma International approves ECMAScript 2024: What’s new? On 26 June 2024, the 127th Ecma General Assembly approved the ECMAScript 2024 language specification, which means that it’s officially a standard now. This blog post explains what’s new. The editors of ECMAScript 2024 # The editors of this release are: Shu-yu Guo Michael Ficarra Kevin Gibbons What’s new in ECMAScript 2024? # Grouping synch
Accurate storage and processing of base-10 decimal numbers is a frequent need in JavaScript. Currently, developers sometimes represent these using libraries for this purpose, or sometimes use Strings. Sadly, JavaScript Numbers are also sometimes used, leading to real, end-user-visible rounding errors. What’s the issue? Why aren’t JS Numbers good enough? In what sense are they not “exact”? How is i
JavaScript Primerのウェブ版がECMAScript 2021に対応しました 🎉 JavaScript Primerのウェブサイトから閲覧できます。 ウェブサイト: https://jsprimer.net/ 対応のサマリIssue: ES2021の対応 · Issue #1220 · asciidwango/js-primer 昨年のES2020のリリースノート: Release 2.0.0: ECMAScript 2020対応 JavaScript Primerについて JavaScript Primerは、これからJavaScriptを学びたい人が、ECMAScript 2015以降をベースにして一からJavaScriptを学べる書籍です。 ECMAScriptの仕様は毎年アップデートされるため、JavaScript Primerも毎年それに対応できるように継続してア
In this TC39 meeting, the updates to JavaScript Classes around private state have moved to stage 4. Other proposals of note this meeting were proposals related to ArrayBuffers, notably resizable ArrayBuffers and a new proposal, introducing read-only ArrayBuffers and fixed views into ArrayBuffers. Read-only ArrayBuffers are not a new ArrayBuffer, but rather a way to freeze existing ArrayBuffers so
Wednesday, August 23, 2023 Dates in JS suck. Well, they suck in all languages, really. It's surprisingly hard to get right. The native Date is super limited. Sure, you can new Date('2015-10-21T01:22:00.000Z') and date.toISOString(), maybe dateA < dateB, but that's pretty much it. Need to add minutes, hours, or whatever to a date, check how many days there are until X date, etc? Good luck with that
Ecma International approves ECMAScript 2022: What’s new? On 22 June 2022, the 123nd Ecma General Assembly approved the ECMAScript 2022 language specification, which means that it’s officially a standard now. This blog post explains what’s new. The editors of ECMAScript 2022 # The editors of this release are: Shu-yu Guo Michael Ficarra Kevin Gibbons What’s new in ECMAScript 2022? # New members of
前 v6.1.0 | 次 v6.3.0 ESLint 6.2.0 has been released: https://t.co/L7srPm1jkE This release adds support for parsing ES2020 features (bigint, dynamic import) using the default parser! Please give it a try and let us know if you see any issues. — ESLint (@geteslint) August 18, 2019 ESLint 6.2.0 がリリースされました。 お盆休み中に ESTree 仕様が更新されたので、BigInt と Dynamic Imports 構文をサポートしました。 既知の問題: babel-eslintを利用している場合、変数の利
The ECMAScript proposal “Import assertions” (by Myles Borins, Sven Sauleau, Dan Clark, and Daniel Ehrenberg) introduces syntax for associating metadata with import statements. In this blog post, we examine what that looks like and why it’s useful. Import assertions # The motivating use case for import assertions was importing JSON data as a module. That looks as follows (and is further specified
The latest update to the XS JavaScript engine continues to focus on adapting and optimizing JavaScript for embedded systems. In this release, the majority of these improvements take place during the preload phase, part of the build process. Additionally, this release adds support for top-level await and WeakRef, two new JavaScript features expected to be part of a future standard. Finally, this re
The triple dot syntax (...) in JavaScript: rest vs. spread In JavaScript, the same syntax – triple dots (...) – is used for two different mechanisms: Rest syntax is for receiving data. Spreading is for sending data. This blog post examines how these mechanisms work and why they are not operators. Receiving data: rest syntax # A rest parameter is a special kind of parameter that receives all remai
Warning: This blog post is outdated. Instead, read section “globalThis” in “JavaScript for impatient programmers”. The ECMAScript proposal “globalThis” by Jordan Harband provides a new standard way of accessing the global object. JavaScript’s global scope # JavaScript’s variable scopes are nested and form a tree whose root is the global scope. That scope is only the direct scope when a script run
ES2023 Features! Array find from last Hashbang Grammar Symbols as WeakMap keys Change array by copy Array find from last Array.prototype.findLast and Array.prototype.findLastIndex 📕 let nums = [5,4,3,2,1]; let lastEven = nums.findLast((num) => num % 2 === 0); // 2 let lastEvenIndex = nums.findLastIndex((num) => num % 2 === 0); // 3Hashbang Grammar #! for JS 📕 The first line of this script begins
Theme 第 78 回のテーマは TC39 です。 今回は Prettier のメンテなや Babel のコントリビュータをやりながら、 TC39 の新しいプロポーサルをそれらに実装する作業をしている @__sosukesuzuki をゲストにお呼びし、 Prettier/Babel のメンテナンスの話などを交え、 TC39 のウォッチの仕方や、気になる Proposal の話、 ES2021 の展望を議論しながら、今後の ES や TC39 について議論しました。 Show Note Prettier - Opinionated Code Formatter Babel - The compiler for next generation JavaScript Web 技術の調査方法 | blog.jxck.io TC39 tc39/proposals tc39/agendas tc3
Update 2020-04-02: Today, the ES2020 candidate was released, with the final feature set of that version. This blog post describes what’s new. A word on ECMAScript versions # Note that since the TC39 process was instituted, the importance of ECMAScript versions has much decreased. What really matters now is what stage a proposed feature is in: Once it has reached stage 4, it can be used safely. Bu
Stage 1 (explanation) Authors: Rob Eisenberg and Daniel Ehrenberg This document describes an early common direction for signals in JavaScript, similar to the Promises/A+ effort which preceded the Promises standardized by TC39 in ES2015. Try it for yourself, using a polyfill. Similarly to Promises/A+, this effort focuses on aligning the JavaScript ecosystem. If this alignment is successful, then a
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