What's the difference between JavaScript engines and JavaScript runtimes? - Human Who Codes
You have probably heard the terms “JavaScript engine” and “JavaScript runtime” used interchangeably to mean “a program that runs JavaScript.” These are often intermixed by referencing V8, Node.js, or some other combination of related programs. However, there is a significant difference between a JavaScript engine and a JavaScript runtime in terms of scope and functionality. Understanding this diff
`export default thing` is different to `export { thing as default }`
`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
GitHub - proposal-signals/proposal-signals: A proposal to add signals to JavaScript.
Stage 0 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 standard could
Recently I landed experimental support for require()-ing synchronous ES modules in Node.js, a feature that has been long overdue. In the pull request, I commented with my understanding about why it did not happen sooner before this pull request in 2024. This post expands on that comment a bit more. The opinions in this post are my own and reflect my perception of the ESM development in Node.js as
依存しているライブラリが ESM only になってしまうことがあると思います。 そんなとき、自分たちが CommonJS だと素直に使えなくて困りますよね。 そこで、なんとかしてCommonJS環境から ESM only のパッケージをrequireする方法をご紹介します。推奨はしません。
【2021/9/1 追記】 提案されていた API のリネームが検討されていましたが ShadowRealm に決まりました。それに伴って記事の中身を修正しています。 【追記ここまで】 Realms とは何か Realms は JavaScript の言語仕様である ECMAScript で定義されている概念です。 JavaScript のコードが評価されるグローバル変数や Array, Map といったビルトインクラス、そこで実行されるコードなどの状態やリソースのことを指します。 ShadowRealm 現在 TC39 で ShadowRealm クラスが提案されています。これを使うことで新しい Realm を作って、JavaScript を評価させることが出来ます。 Web Workers のように別のスレッドで動作されるわけではなく、同じスレッドで同期的に実行されます。 const
JavaScript needs more helper functions for iteration (map, filter, etc.) – where should we put them?
JavaScript needs more helper functions for iteration (map, filter, etc.) – where should we put them? Iteration is a standard that connects operations with data containers: Each operation that follows this standard, can be applied to each data container that implements this standard. In this blog post: We first explore three questions: How does JavaScript’s iteration work? What are its quirks? What
ECMAScript 2019 and beyond...
Newsletter Subscribe to keep up-to-date with the latest content! Last month - June 2019 - 10th edition of ECMA-262 standard was officially published. What does it mean? - Well, ECMAScript 2019 is here! The latest and greatest specification for JavaScript and other derivatives languages to follow. And while you may already have heard of some of its new features, we'll recall all of them! Plus some
The import() operator lets us dynamically load ECMAScript modules. But they can also be used to evaluate JavaScript code (as Andrea Giammarchi recently pointed out to me), as an alternative to eval(). This blog post explains how that works. eval() does not support export and import # A significant limitation of eval() is that it doesn’t support module syntax such as export and import. If we use i
ES2023 / ES2022 / ES2021 もうじき2022年ということで、ES2022にFinished Proposalsとして取り入れられた機能がそれぞれどんなものなのか見てみることにします。 ちなみにFinished Proposalの手前の段階であるStage4が「複数の実装が既に存在する」というのが定義なので、2022という名前にもかかわらず既に一部のブラウザで使用可能、というか一部以外のブラウザで使用可能です。 ES2022 Class Fields Class Fieldsは似たような3RFCの集合体です。 Private instance methods and accessors privateメソッドです。 むしろ今まで存在してなかったことにびっくりだよ。 class Foo{ #privatemethod() { return "privatemethod";
[[toc]] ESM & CJS ESM - ECMAScript modules CJS - CommonJS In the past decade, due to the lack of a standard module system of JavaScript, CommonJS (a.k.a the require('xxx') and module.exports syntax) has been the way how Node.js and NPM packages work. Until 2015, when ECMAScript modules finally show up as the standard solution, the community start migrating to native ESM gradually. // CJS const cir
JavaScript PrimerのES2024の対応を進めていく予定なので、 対応を手伝ってくれるContributorとjsprimerというプロジェクトを支援してくれるSponsorを募集しています。 追記(2024-03-22): Contributorを希望する方は集まりました。ありがとうございます！ JavaScript Primerスポンサーは引き続き募集しています！ Gold Sponsors Supporters 3行サマリー ES2024の対応を6月末までにやるマイルストーンを切りました ES2024の対応を手伝ってくれるContributorを募集しています Open Collectiveを始めたので、プロジェクトを支援してくれるSponsorを募集しています jsprimerのES2024対応 jsprimerは毎年のECMAScriptの仕様改定にあわせてメジャー
ES2023その2 / ES2023 / ES2022 / ES2021 先日ES2023では新機能が2個しかなかったという話をしましたが、どういうわけか2023/01/30になってからES2023が2個追加されました。 よくわかりませんが、どうやら1月までは前年のESになるみたいです。 なんで。 これらは2023/01/30に行われたTC39ミーティングで決定したようです。 他にIntl.NumberFormat V3もStage4への議題に上がったみたいですが、こちらは却下されたみたいです。 なんでそんなふわふわな言及なのかってまだアジェンダしかないから詳しいことがわからねえんだよ。 Finished Proposals Change Array by copy 配列を破壊せずに操作するメソッドを追加します。 既存の配列操作メソッドは、変更後の値を返すと同時に元の値も変更してしまいます
Temporal: getting started with JavaScript’s new date time API Updates: 2022-01-10: Temporal.now was renamed to Temporal.Now. 2021-06-30: Rearranged the content and created a section on the concepts and patterns used by the Temporal API. 2021-06-29: Clarified how Instant uses the ISO-8601 calendar. Listed the properties of some classes. Date, JavaScript’s current date time API is infamously difficu
The proposal “Pipe operator (|>) for JavaScript” (by J. S. Choi, James DiGioia, Ron Buckton and Tab Atkins) introduces a new operator. This operator is an idea borrowed from functional programming that makes applying functions more convenient in many cases. This blog post describes how the pipe operator works and what its use cases are (there are more than you might expect!). The two competing pro
Ecma International approves new standards - Ecma International
Geneva, 8 December 2021 The 122nd General Assembly held in Geneva on 8-9 December 2021 approved the following documents: ECMA-74 19th edition – Measurement of Airborne Noise emitted by Information Technology and Telecommunications Equipment ECMA-352 4th edition – Near Field Communication interface and protocol -2 (NFCIP-2) ECMA-376 5th edition – Part 2: Office Open XML File Formats — Open Packagin
iframe の中で ES Modules のコードを評価する
rollup のような ESM を吐くツールのプレビューツールを作っていると、文字列として組み立てたコードを安全に評価したいことがあります。 方法 iframe を createObjectURL dynamic import で data uri として文字列を評価 得られた関数を実行 コード // これを評価したい const code = `export default () => { console.log("xxx") }`; // 追記:2020/06/24 ユニコード文字対応 const encoded = btoa(unescape(encodeURIComponent(code))); const blob = new Blob( [ `<!DOCTYPE html> <html> <head> </head> <body> <script type=module> im
More information on the syntax and semantics of decorators (optional section) # (This section is optional. If you skip it, you can still understand the remaining content.) The syntax of decorator expressions # A decorator expression starts with a chain of one or more identifiers, separated by dots. Each identifier except the first one can be private (prefix #). Square brackets [] are not allowed
JavaScript 二十年の歴史を森田がひやかします。感想などはハッシュタグ #misreading か hello@misreading.chat にお寄せください。iTunes のレビューや星も歓迎です。 JavaScript: the first 20 years | Proceedings of the ACM on Programming Languages
⭐ Prepare for a JavaScript interview fast with my new book!Learn more → ECMAScript 2020, the 11th installment of our favorite programming language, contains a handful of new features. Some are small ones, but others have the potential to change forever the way we write JavaScript. This article is an attempt at a short and concise overview of those new features. Grab your cup of tea and let's go. D
Array の length の最大値が 2**32-1 のはずだが、配列リテラルの実行時の動作である ArrayAccumulation ではインデックスが ToUint32 を使って 2**32-1 以下でチェックしており、明らかに範囲外アクセスを許容しているのの修正。 コンセンサスが得られた。
Our HOPL paper is done—all 190 pages of it. The preprint will be posted this week. In the meantime, here’s a little teaser. JavaScript: The First 20 Years By Allen Wirfs-Brock and Brendan Eich Introduction In 2020, the World Wide Web is ubiquitous with over a billion websites accessible from billions of Web-connected devices. Each of those devices runs a Web browser or similar program which is ab
Everything You Need to Know About JavaScript Import Maps
Import maps are a new way for web pages to control the behavior of JavaScript imports, potentially enabling you to ditch your build system. In this article, Ayooluwa Isaiah dives deep into the specification.
Snowpack v3.0
Snowpack v3.0 is here! This is our biggest release yet with brand new features including: Pre-bundled streaming imports - Import any npm package, on-demand.Integrated build optimizations - Built-in bundling, preloading, minification, and more.JavaScript API - Integrate with Snowpack’s brand new native JS API.Node.js Runtime API - Import your Snowpack-built files directly into Node.js.Bug fixes, st
LogRocket’s Galileo AI watches every session, surfacing impactful user struggle and key behavior patterns. ECMAScript 2015, also known as ES6, was a major release that took six years to finalize. Since then, Technical Committee 39 (TC39), the body in charge of developing the ECMAScript standard, has been releasing a new edition of the standard every year. This annual release cycle has streamlined
JSer.info #681 - 2024年6月の正式公開に向けたES2024のリリース候補が公開されました。 Release ES2024 Candidate February 2024 · tc39/ecma262 ES2024では、次のような変更が含まれる予定です。 ArrayBuffer.prototype.resize ArrayBuffer.prototype.transfer RegExp v flag Promise.withResolvers Object.groupBy/Map.groupBy Atomics.waitAsync String.prototype.isWellFormed/String.prototype.toWellFormed 毎年2月ごろに仕様へ取り込むProposalが決まり、6月ごろのGA 127th meetingで最終的な承認を得る予定です
ECMAScript 2021
Update 2021-06-22: The 121st Ecma General Assembly approved the ECMAScript 2021 language specification, which means that it’s officially a standard now. This blog post describes what’s new. The editors of ECMAScript 2021 # The editors of this release are: Jordan Harband Shu-yu Guo Michael Ficarra Kevin Gibbons A word on ECMAScript versions # Note that since the TC39 process was instituted, the i
GitHub - tc39/proposal-optional-chaining-assignment: `a?.b = c` proposal
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イントロダクション JavaScript を使う上で非同期処理、特に promise を理解することは非常に重要である。async/await も promise の上に成り立っているので、promise を理解して始めて正しく使うことができる。この記事では JavaScript における非同期処理をどのくらい理解できているかをチェックするための問題を紹介する。 それぞれのコードについて、実行したときにコンソールに何がどういう順序で出力されるかを考えてみよう。なお、コードはブラウザーで実行するものとし、解答は ECMAScript Specification と HTML Living Standard に沿ったものとなっている。 🚗 初級 問題1.1 const p1 = Promise.resolve(1) const p2 = p1.then(x => x * 2) console
GitHub - tc39/proposal-record-tuple: ECMAScript proposal for the Record and Tuple value types. | Stage 2: it will change!
This proposal introduces two new deeply immutable data structures to JavaScript: Record, a deeply immutable Object-like structure #{ x: 1, y: 2 } Tuple, a deeply immutable Array-like structure #[1, 2, 3, 4] Records and Tuples can only contain primitives and other Records and Tuples. You could think of Records and Tuples as "compound primitives". By being thoroughly based on primitives, not objects
Implementing Private Fields for JavaScript – Mozilla Hacks - the Web developer blog
This post is cross-posted from Matthew Gaudet’s blog When implementing a language feature for JavaScript, an implementer must make decisions about how the language in the specification maps to the implementation. Sometimes this is fairly simple, where the specification and implementation can share much of the same terminology and algorithms. Other times, pressures in the implementation make it mor
This Stage 3 proposal is experimental. Do try it and report bugs; don't use it in production! Temporal CookbookOverview Running the cookbook filesRunning cookbook files: see instructions in ../polyfill/README.md Frequently Asked QuestionsThese are some of the most common tasks that people ask questions about on StackOverflow with legacy Date. Here's how they would look using Temporal. Current date
This Stage 3 proposal is experimental. Do try it and report bugs; don't use it in production! Temporal 注: このドキュメントは原文を部分的に日本語に翻訳したものです。全てのドキュメント，および最新の内容を確認したい場合は原文を参照してください。 Table of Contents イントロダクション Cookbook API ドキュメント Temporal.now Temporal.Instant Temporal.ZonedDateTime Temporal.PlainDate Temporal.PlainTime Temporal.PlainDateTime Temporal.PlainYearMonth Temporal.PlainMonthDay Temporal.Duratio
ECMAScript proposal: RegExp flag `/v` makes character classes and character class escapes more powerful
ECMAScript proposal: RegExp flag /v makes character classes and character class escapes more powerful In this blog post, we look at the ECMAScript proposal “RegExp v flag with set notation + properties of strings” by Markus Scherer and Mathias Bynens. The new flag /v # The proposed new regular expression flag /v (.unicodeSets) enables three features: Support for multi-code-point graphemes (such a
ReadSpecWith.us
Read the ECMAScript Specification and understand what it means with code examples!
ESLint v7.2.0 - Qiita
前 v7.1.0 | 次 v7.3.0 ESLint v7.2.0 has been released!https://t.co/8dSO0Hc5X7 — ESLint (@geteslint) June 6, 2020 ESLint 7.2.0 がリリースされました。小さな機能追加とバグ修正が含まれています。 また、日本語のサポートチャットが Gitter から Discord に移動しました。 質問やバグ報告等ありましたら、お気軽にこちらまでお寄せください。 🏢 日本語 Issue 管理リポジトリ 👫 日本語サポート チャット (招待リンク) 🏢 本家リポジトリ 👫 本家サポート チャット (招待リンク) [PR] ESLint は開発リソースを確保するための寄付を募っています。 応援してくださると嬉しいです。 ESLint の GitHub Sponsors 私個人の Git
GitHub - billinghamj/fix-es-imports: Fixes your ES import paths - from Node-style to explicit filenames
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GitHub - tc39/proposal-uuid: UUID proposal for ECMAScript (Stage 1)
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We recently shipped import maps in Firefox 108 and this article is the first in a series that describes what they are and the problems they can solve. In this first article, we will go through the background and basics of import maps and follow up with a second article explaining more details of import maps. Background: JavaScript Modules If you don’t know JavaScript modules, you can read the MDN
The changes of proposal’s status @ 70th meeting of Ecma TC39 New Proposals None Updated Proposals Proposal From To
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require(esm) in Node.js
ESM移行は無理だけどおれもSindreのライブラリが使いたい！
ECMAScript Realms と ShadowRealm の提案 - Qiita
Evaluating JavaScript code via `import()`
【JavaScript】ES2022の新機能 - Qiita
Ship ESM & CJS in one Package
JavaScript PrimerのES2024対応を手伝ってくれるContributorとSponsorを募集しています
【JavaScript】ES2023の新機能が何故かいまさら追加されていた - Qiita
Temporal: getting started with JavaScript’s new date time API
A pipe operator for JavaScript: introduction and use cases
JavaScript metaprogramming with the 2022-03 decorators API
#86: JavaScript: the first 20 years
What's new in ECMAScript 2020
2019-10 の TC39 meeting - moriken's project
Teaser—JavaScript: The First 20 Years
5 ES2019 features you can use today - LogRocket Blog
2024-02-20のJS: ES2024 RC、typescript-eslint v7、React Compiler
何問分かる？Promise に関するクイズ13問【解説付き】 - Qiita
Temporal documentation
Temporal documentation
JavaScript Import maps, Part 1: Introduction
ECMAScript proposal updates @ 2019-06