TC39 に新設された Stage 2.7 について | blog.jxck.io
Intro TC39 の Stage 2 と Stage 3 の間に、新たに Stage 2.7 が追加された。 これは何だろうと思った人が検索で辿り着けるよう、その経緯と目的をまとめる。 TC39 Stages TC39 は、ECMAScript (つまりまあ JS) の新機能を議論する Task Group だ。 ここでは、比較的自由に新機能の提案がなされ、定期的に行われるミーティングでの議論や、実装からのフィードバックを経て、Stage が上がっていく仕組みをとっている。 旧来の Stage は 0~4 まであった。ざっくり言うと以下のようなものだ。
TypeScript 5.2's New Keyword: 'using'
Matt PocockMatt is a well-regarded TypeScript expert known for his ability to demystify complex TypeScript concepts. TypeScript 5.2 introduces a new keyword - using - that you can use to dispose of anything with a Symbol.dispose function when it leaves scope. { const getResource = () => { return { [Symbol.dispose]: () => { console.log('Hooray!') } } } using resource = getResource(); } // 'Hooray!'
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
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
JavaScript metaprogramming with the 2022-03 decorators API
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
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 updates @ 2021-08
ECMA-402 New Proposals No Data Updated Proposals No Data This diff is generated by ECMAScript Proposal Diff Tool. Agenda Agendas Babel babel/proposals: Tracking the status of Babel’s implementation of TC39 proposals August 2021 · Issue #76 · babel/proposals Other proposal’s status tc39/proposals: Tracking ECMAScript Proposals Related services ECMAScript Proposal Diff Tool tc39/dataset: The automat
Temporal: getting started with JavaScript’s new date time API
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
ECMAScript 2020: the final feature set
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
ECMAScript proposal updates @ 2019-12
The changes of proposal’s status @ 73th meeting of Ecma TC39 New Proposals Proposal Stage
Weak references and finalizers · V8
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
ECMAScript proposal updates @ 2019-06
The changes of proposal’s status @ 70th meeting of Ecma TC39 New Proposals None Updated Proposals Proposal From To
ECMAScript proposal updates @ 2019-03
The changes of proposal’s status @ 69th meeting of Ecma TC39 New Proposals Proposal Stage
Feature watch: ECMAScript 2019
Update 2019-01-29: The feature set of ECMAScript 2019 is now final (source) and described in this blog post. 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. But even then, you still have to ch
SmooshGate FAQ | Blog | Chrome for Developers
What the smoosh happened?! A proposal for a JavaScript language feature called Array.prototype.flatten turns out to be Web-incompatible. Shipping the feature in Firefox Nightly caused at least one popular website to break. Given that the problematic code is part of the widespread MooTools library, it’s likely that many more websites are affected. (Although MooTools is not commonly used for new web
ECMAScriptの仕様/プロポーザルの調べ方を知る
このステージの詳細についてはThe TC39 Processを参照してください。 2ヶ月に1度行われるTC39のミーティングにおいて、プロポーザルごとにステージを進めるかどうかを議論します。 このミーティングの議事録もGitHub上のtc39/tc39-notesにて公開されています。 ステージ4となったプロポーザルはドラフト版であるtc39/ecma262へマージされます。 そして毎年の決まった時期にドラフト版を元にしてECMAScript 20XXとしてリリースします。 この仕様策定プロセスの変更は、ECMAScriptに含まれる機能の形にも影響しています。 たとえば、class構文の策定は最大限に最小のクラス（maximally minimal classes）と呼ばれる形で提案されています。 これによりES2015でclass構文が導入されましたが、クラスとして合意が取れる最低限の
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ECMAScript proposal updates @ 2024-06
ECMAScript proposal updates @ 2020-04
ECMAScript proposal updates @ 2020-02 | ECMAScript Daily
ECMAScript proposal: private class fields