What's actually new in JavaScript (and what's coming next)
What's actually new in JavaScript (and what's coming next) ES2025 is out, ES2026 is close. Here is the new feature of Javascript we can use today, what is coming next and how we can get our AI friends to use these new features Hi there, it's Dan, a technical co-founder of an ed-tech startup, host of Señors at Scale - a podcast for Senior Engineers, Organizer of ReactJS Barcelona meetup, internatio
GitHub - tc39/proposal-signals: A proposal to add signals to JavaScript.
Stage 1 (explanation) TC39 proposal champions: Daniel Ehrenberg, Yehuda Katz, Jatin Ramanathan, Shay Lewis, Kristen Hewell Garrett, Dominic Gannaway, Preston Sego, Milo M, Rob Eisenberg Original 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 i
GitHub - tc39/faq
This document contains typical responses to questions that are commonly raised about JavaScript language development, both within the community and to the committee via our various discussion platforms. Anyone may suggest new topics by opening an issue. Delegates may add new topics by creating a Pull Request. If a delegate disagrees with one of these topics, it should be removed. It can be re-adde
TypeScript 5.2で予告されているusingをいじってみる
この記事でのusing宣言の動作はBabelのtransform及びes-shimsのpolyfill実装に依存しており、実際のV8エンジンやTypeScriptのトランスパイル出力の挙動とは異なる可能性があります。 以下の挙動がusing宣言に対応している処理系の実際の挙動と異なる場合はコメントをいただけると幸いです。 導入 先日、Twitterでこんなツイートが回ってきました。 TypeScript 5.2で新しい「using宣言」が追加されるというものです。 しかも、TypeScriptの独自構文かと思いきや、JavaScriptのStage 3のProposalをTypeScriptで先行実装するという通常のTypeScriptの実装プロセスに則ったものでした。 新しい変数宣言の追加はES 2015(ES6)の「let」「const」以来でなんと8年ぶりで、JavaScript/T
ES2023 features list
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
ECMAScript 2025 feature: Set methods
In this blog post, we examine the ECMAScript proposal “Set methods for JavaScript” by Michał Wadas, Sathya Gunasekara and Kevin Gibbons. It introduces new methods for Sets. New Set methods that return Sets # Set.prototype.union(other) # This method returns a Set that is the union of this and other. Type signature: Set<T>.prototype.union(other: SetReadOperations<T>): Set<T> The type of other, Set
今のうちに Module Expressions と Module Declarations について整理しておこう
筆者は次の 2 つの ECMAScript のプロポーザルに注目しています。 Module Expressions Module Declarations この 2 のプロポーザルは構文のみに注目するとよく似ています。しかしそのモチベーションは全く異なります。 このプロポーザルが登場したのは 2 年ほど前ですが、現在でも仕様の策定が進んでいます。これらのプロポーザルが順調に進捗し ECMAScript に取り込まれることに備えて、それらのモチベーションを今のうちに整理しておきましょう。 まず Module Expressions も Module Declarations も、モジュールの中で新しいモジュールを作成する構文を導入するプロポーザルです（名前から想像できるとおり）。 // Module Expressions の例 const mod1 = module { export co
ECMAScript proposal: iterator helpers
Update 2022-12-15: New section “How will this proposal affect future JavaScript APIs?” In this blog post, we look at the ECMAScript proposal “Iterator helpers” by Gus Caplan, Michael Ficarra, Adam Vandolder, Jason Orendorff, Kevin Gibbons, and Yulia Startsev. It introduces utility methods for working with iterable data: .map(), .filter(), .take(), etc. The style of the proposed API clashes with th
Record & Tuples から派生した JSON.parseImmutable というプロポーザルがよさそう
Records & Tuples というそこそこ有名(?)なプロポーザルがありますが、そのプロポーザルから派生した JSON.parseImmutable という新しいプロポーザルが良さそうなので紹介します。 Records & Tuples Records & Tuples はレコードとタプルという新しいデータ構造を導入する現在 Stage 2 のプロポーザルです。 レコードとタプルは、それぞれイミュータブルなオブジェクトと配列のようなものです。現在提案されている構文では通常のオブジェクトリテラルや配列リテラルの頭に # をつけると、レコードとタプルになります。 const record = #{ x: 1, y: 2, }; const tuple = #[1, 2, 3]; レコードやタプルやイミュータブルなデータ構造なので後から内容を更新することはできません。 レコードとタプルの大
ECMAScript proposal: `Array.fromAsync()`
This blog post is about the ECMAScript proposal “Array.fromAsync for JavaScript” by J. S. Choi. It introduces a static method for converting asynchronous iterables to Arrays. Tools for working with synchronous iterables # Currently JavaScript provides several tools for working with synchronous iterables – for example: function* createSyncIterable() { yield 'a'; yield 'b'; yield 'c'; } // Array-de
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
ECMAScript proposal “Change Array by copy”: four new non-destructive Array methods
ECMAScript proposal “Change Array by copy”: four new non-destructive Array methods This blog post describes the ECMAScript proposal “Change Array by copy” by Robin Ricard and Ashley Claymore. It proposes four new methods for Arrays and Typed Arrays: .toReversed() .toSorted() .toSpliced() .with() The new methods are for Arrays and TypedArrays # This blog post only demonstrates the new methods with
ECMAScript proposal: searching Arrays from end to start via `.findLast()` and `.findLastIndex()`
ECMAScript proposal: searching Arrays from end to start via .findLast() and .findLastIndex() This blog post describes the ECMAScript proposal “Array find from last” by Wenlu Wang and Daniel Rosenwasser. Topic of this blog post: methods of Arrays and of Typed Arrays # In this blog post, we explore methods of Arrays. But everything we learn also applies to Typed Arrays. Searching Arrays # The foll
GitHub - tc39/proposal-explicit-resource-management: ECMAScript Explicit Resource Management
NOTE: This proposal has subsumed the Async Explicit Resource Management proposal. This proposal repository should be used for further discussion of both sync and async of explicit resource management. This proposal intends to address a common pattern in software development regarding the lifetime and management of various resources (memory, I/O, etc.). This pattern generally includes the allocatio
ES2022 feature: class static initialization blocks
The ECMAScript proposal “Class static initialization blocks” by Ron Buckton is at stage 4 and scheduled to be included in ECMAScript 2022. For setting up an instance of a class, we have two constructs in JavaScript: Field: Create (and optionally initialize) instance properties. Constructor: A block of code that is executed before setup is finished. For setting up the static part of a class, we onl
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GitHub - tc39/proposal-optional-chaining-assignment: `a?.b = c` proposal
GitHub - tc39/proposal-promise-with-resolvers
ECMAScript proposal: source text access for `JSON.parse()` and `JSON.stringify()`
GitHub - tc39/proposals: Tracking ECMAScript Proposals
GitHub - daumann/ECMAScript-new-features-list: A comprehensive list of new ES features, including ES2015 (ES6), ES2016, ES2017, ES2018, ES2019
