Rob Palmer
@robpalmer2
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JavaScript Infrastructure & Tooling at Bloomberg. Co-chairing @TC39 . Likely to tweet tech stuff about JS & software performance. Opinions are my own.
London, England
Joined July 2009
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![[H] CEK FAV NYA YA!](https://pbs.twimg.com/profile_images/584988285551841280/29u3eDkn.jpg)
ECMAScript excitement 😉
Today TC39 advanced these features to Stage-4 🎉
- Intl.ListFormat
- Intl.DateTimeFormat: dateStyle & timeStyle
- Logical Assignment (&&= ||= ??=)
- Numeric Separators (1_000)
- Promise.any & AggregateError
- WeakRefs & FinalizationRegistry
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350
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ECMAScript excitement 😉
ES2021 has been approved by the Ecma General Assembly 🎉
💡 Logical Assignment Operators (&&= ||= ??=)
💡 Numeric Separators (1_000)
💡 Promise.any & AggregateError
💡 String.prototype.replaceAll
💡 WeakRefs & FinalizationRegistry
9
192
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ECMAScript excitement 😉
TC39 has advanced the Record & Tuple proposal to Stage 2!
This brings immutable datastructures to JavaScript.
Congrats to my colleagues
@TechAtBloomberg
@r_ricard
@rickbutton
@NicoloRibaudo
who are championing the proposal.
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Two proposals hit Stage 3 at TC39 this week.
?? 🔥 Nullary Coalescing
?. 🔥 Optional Chaining
Get ready for more question marks in your JS!
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ECMAScript excitement 😉
Congrats to
@smooshMap
on advancing Iterator Helpers to Stage 3 at
@TC39
today 🎉
Both sync & async iterators gain these methods:
🔸 map
🔸 filter
🔸 take
🔸 drop
🔸 flatMap
🔸 reduce
🔸 toArray
🔸 forEach
🔸 some
🔸 every
🔸 find
11
100
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ECMAScript excitement 😉
ES2022 is approved by Ecma International 🎉
🔶 Class Fields
🔶
#field
in obj checks
🔶 Class Static Blocks
🔶 .at() for arrays & strings
🔶 Error Cause
🔶 Object.hasOwn()
🔶 RegExp Match Indices (/d)
🔶 Top Level Await
15
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ECMAScript excitement 😉
Congrats to
@acutmore
on advancing TC39 proposal "Change Array by Copy" to Stage 3 🎉
These new array methods return a fresh array, leaving the original unmodified.
🔹 .with()
🔹 .toReversed()
🔹 .toSorted()
🔹 .toSpliced()
5
102
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ECMAScript excitement 😉
Today the Ecma General Assembly approved ES2024 🎉
🔶 Array.groupBy & Object.groupBy
🔶 ArrayBuffer transfer
🔶 Atomics.waitAsync
🔶 Promise.withResolvers
🔶 RegExp v flag
🔶 Resizable ArrayBuffers
🔶 Well-Formed Unicode Strings
4
82
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ECMAScript excitement 😉
Next week's
@TC39
meeting is hosted by
@TechAtBloomberg
in Tokyo & has a packed agenda:
🔸 AsyncContext
🔸 Decimal
🔸 Import Attributes
🔸 Intl.MessageFormat
🔸 Negated `in`
🔸 Pattern Matching
🔸 Structs
🔸 TDZ
🔸 Throw expressions
🔸 Type Annotations
14
67
382
Source Maps have caused too many unnecessarily frustrating debugging situations.
I'm super pleased we're now investing in hardening the spec and the ecosystem tools to make JS debugging a first-class experience.
TC39 has formed a new Task Group to standardize Source Maps.
Source Maps are a file format used for debugging and post-hoc analysis of JavaScript and other languages.
The convenors of TC39-TG4 are
@jkup
and
@littledan
.
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ECMAScript excitement 😉
Congrats to
@bakkoting
on advancing Set Methods to Stage 4 this week
@TC39
🎉
Set.prototype gains these methods:
🔶 intersection
🔶 union
🔶 difference
🔶 symmetricDifference
🔶 isSubsetOf
🔶 isSupersetOf
🔶 isDisjointFrom
8
62
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📢I wrote a blog post on how
@TechAtBloomberg
uses TypeScript.
"10 Insights from Adopting TypeScript at Scale"
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ECMAScript excitement 😉
Congrats to
@acutmore
@TechAtBloomberg
on advancing "Change Array by Copy" to Stage 4
@TC39
🎉
These new array methods return a fresh array leaving the original unmodified.
🔹 toReversed()
🔹 toSorted()
🔹 toSpliced()
🔹 with()
8
74
334
Prettier will be 5x faster thanks to
@fabiospampinato
🔥
For cached usage the win is 22x so far 😮
Zero Rust. This is top-tier JS performance work, described in detail in the blog post. Learn about efficient globbing, minimizing FS access, work-skipping, caching.
This is gold.
As a direct result of the bounty,
@fabiospampinato
has been rewriting the prettier CLI to be orders of magnitude faster. Please try it out and check this awesome performance deep dive:
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ECMAScript excitement 😉
Congrats to
@NicoloRibaudo
on advancing Optional Chaining for assignments to Stage 1
@TC39
today 🎉
Today Optional Chaining works on the Right-Hand Side of assignment.
value = obj?.prop
This proposal allows it on the left 👍
obj?.prop = value 🆕
4
46
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bun is a new JavaScript runtime 🎉
↔️ An alternative to existing runtimes like Node, Deno, etc
🔋 Batteries Included - the toolchain has compilation, bundling, testing, npm fetching
🍎 Uses JSC engine (not V8)
⚡ Written in Zig (not Rust/C++)
🔥 Super fast
By
@jarredsumner
Introducing Bun - an incredibly fast all-in-one JavaScript runtime.
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ECMAScript excitement 😉
Congrats to my coworker
@peetklecha
@TechAtBloomberg
on advancing the Promise.withResolvers() proposal to Stage 2
@TC39
today 🎉
It creates a promise with exposed functions to resolve or reject it. Also known as a "Deferred" 👍
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TypeScript source code now uses ES modules 🎉
🔹 npm package is 46% smaller
🔹 Build times reduced by 10-25% 😲
The next likely step is to ship native ESM for even more wins 👍
e.g. making the CJS entrypoint a thin wrapper around a native ESM entrypoint will save 7 MB alone 🔥
Want to hear about our refactoring adventures?
We put together a nice short write-up (just 6,000 words) about our journey in modernizing the TypeScript codebase, and our migration to modules!
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ECMAScript excitement 😉
@TC39
advanced these proposals this week 🎉
4️⃣ Atomics.waitAsync
4️⃣ RegExp v flag
4️⃣ Well-Formed Unicode Strings
3️⃣ Decorator Metadata
3️⃣ Float16Array
2️⃣ Base64 for Uint8Array
2️⃣ Promise.withResolvers
2️⃣ TimeZone Canonicalizn
1️⃣ Intl.ZonedDateTimeFormat
7
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ECMAScript excitement 😉
These proposals achieved stage advancement during this week's 90th TC39 meeting 🎉
4️⃣ findLast/findLastIndex
3️⃣ Symbols as WeakMap keys
3️⃣ JSON.parse source text access
3️⃣ RegExp modifiers
2️⃣ String.dedent
1️⃣ Import Reflection
1️⃣ RegExp Atomic Operators
8
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ECMAScript excitement 😉
This week's
@tc39
agenda:
🔶 Array.isTemplateObject
🔶 AsyncContext
🔼 Decimal
🔼 Deferred Evaluation
🔶 Explicit Res Mgmt
🔼 Extractors
🔼 Iterator.range
🔼 Math.sumExact
🔼 Pattern Matching
🔶 Record & Tuple
🔼 Set Methods
🔶 Shared Structs
🆕 Signals
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Typescript 4.5 is on track to support the native ES Module features introduced in Node 12 thanks to Wes Wigham 🎉
🔥 *.mjs & *.cjs files are importable
🔥 "type": "module" in package.json
🔥 "exports" in package.json
🔥 native import() in CJS files
5
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ECMAScript excitement 😉
Congrats to my coworker
@peetklecha
@TechAtBloomberg
for advancing Promise.withResolvers to Stage 4
@TC39
today 🎉
const { promise, resolve, reject } =
Promise.withResolvers();
Also known as a "Deferred"
4
52
294
ECMAScript excitement 😉
Congrats to
@bakkoting
on advancing the Set Methods proposal to Stage 3 at
@TC39
today 🎉
Set.prototype gains these methods:
🟡intersection
🟡union
🟡difference
🟡symmetricDifference
🟡isSubsetOf
🟡isSupersetOf
🟡isDisjointFrom
4
51
292
ECMAScript excitement 😉
ES2023 was approved by Ecma International at the 125th General Assembly in Geneva 🎉
Featuring...
🔶 Array findFromLast()
🔶 Change Array by Copy
🔶 Hashbang Grammar
🔶 Symbols as WeakMap keys
4
36
291
ECMAScript excitement 😉
TC39 has advanced these proposals.
💡Resizable ArrayBuffers➡️2
💡Error Cause➡️1
💡Double-Ended Iterator & Destructuring➡️1
💡Intl.DisplayNames V2➡️1
💡Intl Locale Info➡️1
💡Modulus & Additional Integer Math➡️1
💡Standardized Debug➡️1
💡String Dedent➡️1
6
81
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ECMAScript excitement 😉
Congrats to
@pzuraq
on advancing TC39 proposal Decorators to Stage 3 🎉
This is conditional advancement based on separating out metadata into a follow-on proposal.
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TypeScript excitement 😉
Congrats to
@TitianCernicova
@TechAtBloomberg
on landing --isolatedDeclarations in upstream TypeScript 🎉
It's the start of a journey to faster type-checking at scale 🔥
An epic collab between folk in TS, Bloomberg & Google 👍
10
45
287
ECMAScript excitement 😉
TC39 has just advanced these proposals 🎉
- Class static initialization block ➡️ Stage 2
- .item() for indexables ➡️ Stage 3
- Import Assertions ➡️ Stage 3
- Intl.DisplayNames ➡️ Stage 4
- Intl.Enumeration ➡️ Stage 2
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82
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📢 LLRT (Low Latency Runtime) is a new JS runtime from Amazon ✨
⚡ Designed for fast Serverless startup time
🦀 Written in Rust
💨 Embeds the QuickJS engine written in C
💡 Lightweight (~3MB)
🧪 Experimental!
6
70
280
ECMAScript excitement 😉
This week
@TC39
advanced these proposals 🎉
3️⃣ Array Grouping
3️⃣ Promise.withResolvers
3️⃣ Source Phase Imports
3️⃣ Time Zone Canonicalization
2️⃣ Deferred Import Evaluation
1️⃣ DataView get/set Uint8Clamped methods
1️⃣ Optional Chaining assignment
3
75
280
TypeScript 5.5 is out 🎉
🔶 JS: Set Methods
🔷 Checking: Inferred type predicates
🔷 Checking: RegExp syntax
🔷 JSDoc: Type Imports
🔷 DTS: Isolated Declarations
🔷 DTS: transpileDeclaration API
🔷 Config: ${configDir}
🔷 Package: Shrinks 30%
🗑 Deprecated flags
TypeScript 5.5 is now available! 🎉✨
Now with
✅ Inferred Type Predicates
✅ RegEx syntax checks
✅ The JSDoc @import Tag
✅ ${configDir} for easier tsconfig inheritance
✅ --isolatedDeclarations
✅ Lots of new optimizations
And more! Try it today!
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ECMAScript excitement 😉
These proposals advanced
@TC39
this week 🎉
3️⃣ Async Explicit Resource Mgmt
3️⃣ Import Attributes (*)
2️⃣ AsyncContext
2️⃣ Float16Array
2️⃣ Iterator.range
1️⃣ Await Dictionary
1️⃣ Class Method Param Decorators
1️⃣ Promise.withResolvers
1️⃣ TZ Canonicalization
5
59
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ECMAScript excitement 😉
These proposals moved this week
@TC39
🎉
4️⃣ Resizable ArrayBuffer
2️⃣ RegExp.escape
2️⃣🔙 ShadowRealm
1️⃣ Joint Iteration
1️⃣ Locale Extensions
1️⃣ Iterator Sequencing
1️⃣ Negated in
1️⃣ Stable Formatting
🗑️ FinalizationRegistry
#cleanupSome
🗑️ Symbol.thenable
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ECMAScript excitement 😉
TC39 proposal Temporal is now Stage-3 🎉
It's about time ⏰ and provides a replacement for Date 📅
Congrats to all the champions & contributors
@maggiepint
@pipobscure
@mj1856
@bterlson
@_sffc
@ryzokuken
@therealptomato
@Jason_williams
@justingrantjg
Hurray!!! The JavaScript Temporal proposal has reached stage 3 in TC39. Proper Date & Time handling are coming!
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0
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ECMAScript excitement 😉
New proposal Records & Tuples achieved Stage 1 at TC39! This brings immutable datastructures to JS.
Congrats to champions
@r_ricard
and
@rickbutton
4
89
247
Google Earth is now using WebAssembly to avoid depending on Chrome-specific features.
1
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ECMAScript excitement 😉
This week
@TC39
advanced these proposals 🎉
4️⃣ ArrayBuffer transfer
3️⃣ Base64 conversion
2️⃣.7️⃣ ShadowRealm
2️⃣ Joint Iteration
2️⃣ Math.sum
2️⃣ Promise.try
1️⃣ Discard bindings
1️⃣ ESM Phase Imports
1️⃣ Function Decorators
1️⃣ Iterator Unique/Chunking
4
36
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ECMAScript excitement 😉
Congrats to
@JatinRamanathan
@littledan
&
@wycats
on advancing the Signals proposal to Stage 1 today
@TC39
🎉
Thanks to proposal author
@EisenbergEffect
and the many other framework representatives who have contributed so far 👍
Achievement Unlocked! Signals advance to Stage 1 in TC39.
Big thanks to
@JatinRamanathan
,
@littledan
, and
@wycats
for presenting today.
Lots more work to do during Stage 1, but we're now officially under consideration.
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ECMAScript excitement 😉
This week TC39 advanced these proposals 🎉
3️⃣ Change Array by Copy
3️⃣ Decorators
3️⃣ RegExp set notation + string props
2️⃣ Decorators metadata
1️⃣ Function.prototype.once()
1️⃣ Intl units conversion
1️⃣ Intl.MessageFormat
1️⃣ Type Annotations
3
51
226
Typescript 4.5 is on track to support explicit type-only import specifiers thanks to
@atcb
🎉
📘 import { a, type b } from "p"
➡️
📙 import { a } from "p"
This use of `type` conveys more information to the reader and will simplify tooling.
4
50
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ECMAScript excitement 😉
This week
@TC39
advanced these JS proposals 🎉
4️⃣ Array Grouping
4️⃣ Promise.withResolvers()
1️⃣ Module sync assert
...and withdrew these proposals
🗑️ Operator Overloading
🗑️ Custom Numeric Suffices
5
28
216
ECMAScript excitement 😉
This week
@TC39
advanced these proposals 🎉
4️⃣ RegExp: Duplicate Named Cap Groups
4️⃣ Set Methods
3️⃣ eval for Trusted Types
3️⃣ eval-injected global var is redeclarable
2️⃣.7️⃣ Math.sumPrecise
2️⃣.7️⃣ Promise.try
1️⃣ Error.isError
1️⃣ Signals
1️⃣ Strict `using`
12
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ECMAScript excitement 😉
Import Assertions will (pending editorial reviews) re-advance to Stage 3 under the new name "Import Attributes" 🎉
The `assert` keyword is now renamed to `with`
import obj from "mod" with { "type": "json" }
`assert` will be deprecated ⚠
5
50
214
ECMAScript excitement 😉
Congrats to
@evanwallace
on shipping support for
@TC39
Stage 3 Decorators in esbuild v0.21 🎉
Evan's diligent approach led to bugs being reported in Babel, TypeScript, SWC, plus clarification in the forthcoming ES spec text 👍
3
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ECMAScript excitement 😉
Congrats to
@rbuckton
on landing
@TC39
Stage 3 Decorators in
@typescript
heading for TypeScript 5.0 🎉
Thanks to the reviewers
@sanders_n
@drosenwasser
@ahejlsberg
@JLHwung
@WesleyWigham
@sheetalkamat
👍
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@TheBrousse
@varjmes
@pujux_
@zyxwvutswal
@yagiznizipli
@guykdm
Yagiz is a kind person who has donated extreme amounts of his free time to improving Node performance without payment, because he wants to lift up the community.
I'm impressed how reasonable his responses are given the wild assertions being made here.
1
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TypeScript 5.4 is out 🎉
🔶 JS: Object.groupBy & Map.groupBy
🔷 Checking: Closure bindings narrowed after final assignment
🔷 Checking: "NoInfer" utility type
🔷 Checking: Customizable Import Attributes
🔷 Modules: require() in ESM
🔷 IDE: Quick fix missing params
Announcing TypeScript 5.4! 📢
Now with:
✅ Smarter control-flow analysis in closures
✅ The `NoInfer` utility type
✅ Broader support for bundlers and runtimes
✅ Quick fixes for missing parameters
✅ Improved auto-imports
and more! Try it today!
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If you say "Type Annotations" three times, this guy suddenly appears 😉
3
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TypeScript 5.5 RC is out 🎉
🔶 JS: Set Methods
🔷 Checking: Inferred type predicates
🔷 Checking: RegExp syntax
🔷 JSDoc: Type Imports
🔷 DTS: Isolated Declarations
🔷 DTS: transpileDeclaration API
🔷 Config: ${configDir}
🔷 Package: Shrinks 30%
🗑 Deprecated flags
TypeScript 5.5 RC is now out to try! We're looking for feedback on inferred type predicates, JSDoc imports, regex checking, ${configDir}, isolatedDeclarations, build optimizations, and more!
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ECMAScript excitement 😉
These proposals achieved stage advancement at this week's
@TC39
meeting 🎉
⏩3️⃣ Array.fromAsync
⏩2️⃣ Well-Formed Unicode Strings
⏩1️⃣ Extractors
2
42
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JavaScript engines are much like buses: you wait years for one, then two shiny new ones show up at once!
🔥 QuickJS by Fabrice Bellard
🔥 Hermes by Facebook
3
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ECMAScript excitement 😉
TC39 Stage 0 proposal BigDecimal for arbitrary-precision decimal numbers has been implemented in the QuickJS engine made by Fabrice Bellard.
0.1d + 0.2d === 0.3d // true!
8
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Profiling production code in
@ChromeDevTools
now shows you original function names in Chrome 109 🎉
This uses sourcemaps to decode the minified function name.
Thanks to Andres Olivares for implementing this 👍
4
41
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ECMAScript excitement 😉
TC39 Stage 2 proposal Record & Tuple brings immutable data structures to JavaScript that can be compared by value.
#{ a:1 } === #{ a:1 } // true 🔥
@r_ricard
from
@TechAtBloomberg
will reveal more at
@thejsnation
in Amsterdam in June.
2
42
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ECMAScript excitement 😉
Congrats to
@giltayar
& my fellow champions
@drosenwasser
@romulocintra
on advancing TC39 proposal "Type Annotations" to Stage 1 🎉
This proposal was formerly known as "Types as Comments"
Hopefully this will make using typed JavaScript even easier 🎈
3
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ECMAScript excitement 😉
Chrome 119 is released 🎉
🔸 Stage 3 Promise.withResolvers()
🔹 WebAssembly Garbage Collection (WasmGC)
3
26
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ECMAScript excitement 😉
This week
@TC39
moved these proposals 🎉
4️⃣ Change Array by Copy
4️⃣ Intl.NumberFormat V3
4️⃣ Symbols as WeakMap keys
3️⃣ ArrayBuffer transfer
2️⃣⏪ Import Assertions
2️⃣ Intl era/monthCode
2️⃣ Symbol Predicates
1️⃣ Async Context
1️⃣ Proto pollution mitigation
4
33
192
ECMAScript excitement 😉
This week
@TC39
advanced these proposals 🎉
3️⃣ Promise.try
2️⃣.7️⃣ Deferred Import Evaluation
2️⃣.7️⃣ Joint Iteration
2️⃣.7️⃣ RegExp.escape
2️⃣ Error.isError
2️⃣ ESM Phase Imports
2️⃣ Discard Bindings
2️⃣ Iterator Sequencing
3
33
192
TypeScript 4.9 Beta is out 🎉
🔷 New `satisfies` operator to check compatibility
🔷 Enhanced narrowing of `in`
🔷 Stricter NaN checks
🔶 File-Watching is more efficient - reduced polling
🔶 No more speculative import-specifier-elimination in JS files
TypeScript 4.9 Beta is now available! Try out our improved 'in' operator narrowing, the new 'satisfies' operator, stricter 'NaN' checks, and more-efficient file-watching defaults!
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ECMAScript excitement 😉
Optional Chaining just achieved Stage 4 at TC39!
Many people worked on this including
@drosenwasser
@the_gisenberg
@DustinSavery
@devsnek
@ioctaptceb
@rkirsling
@BenjaminCoe
@littledan
Joshua Litt, Claude Pache, Justin Ridgewell
Optional Chaining just moved to Stage 4 at TC39! 🎉
?. is now part of ES2020!
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This is big.
@guybedford
has managed to get Node to synthesise named exports from classic CommonJS modules 🎉
import { prop } from "cjs-module"
Many users have requested this for years.
🎉Happy
@nodejs
release day 🎉
OMG named imports from CJS modules edition! Congrats
@guybedford
on getting this together.
$ nvm install v14.13.0
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ECMAScript excitement 😉
Safari 17.0 ships support for
@TC39
Stage 3 proposal Set Methods 🎉
The seven new Set.prototype methods are:
🔸 intersection
🔸 union
🔸 difference
🔸 symmetricDifference
🔸 isSubsetOf
🔸 isSupersetOf
🔸 isDisjointFrom
0
31
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If you are interested in low-level JS performance optimization techniques that exploit monomorphism & JIT,
@TitianCernicova
just dropped an experimental win of ~20% in the TypeScript checker 🔥
This kind of win does not get discovered everyday.
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ECMAScript excitement 😉
A strong agenda for tomorrow's TC39 meeting 🔥
💡 Array Grouping (requesting Stage 3⃣)
💡 Decimal numbers
💡 Decorators
💡 New Intl APIs
💡 Records & Tuples
💡 RegExp enhancements
💡 ShadowRealms
💡 Temporal date/times
4
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ECMAScript excitement 😉
Nullish Coalescing just achieved Stage 4 at TC39.
Congrats to
@drosenwasser
@the_gisenberg
@littledan
@rkirsling
@rbuckton
@sheetalkamat
@AngelC07243045
@devsnek
Joshua Litt, Justin Ridgewell
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TypeScript excitement 😉
Today TS 5.5 ships Isolated Declarations 🎉
An epic collab between
@TechAtBloomberg
@Google
@typescript
to enhance .d.ts emit & unlock performance 🔥
Thanks to
@TitianCernicova
Hana Joo
@TChetwin
@frigus02
Lisa Velden
@andhaveaniceday
@WesleyWigham
👍
TypeScript 5.5 is out 🎉
🔶 JS: Set Methods
🔷 Checking: Inferred type predicates
🔷 Checking: RegExp syntax
🔷 JSDoc: Type Imports
🔷 DTS: Isolated Declarations
🔷 DTS: transpileDeclaration API
🔷 Config: ${configDir}
🔷 Package: Shrinks 30%
🗑 Deprecated flags
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TypeScript 5.5 Beta is out 🎉
🔷 Checking: Inferred type predicates
🔷 Checking: RegExp syntax
🔷 JSDoc: Type-only imports
🔷 DTS: Isolated Declarations
🔷 DTS: transpileDeclaration API
🔷 DTS: Omit references by default
🔷 Package: 30% smaller install
🗑 Deprecated flags
Announcing TypeScript 5.5 Beta! 📣
Now with type predicate inference, more type narrowing, an @import tag for JSDoc, the --isolatedDeclarations flag, performance & reliability improvements, and much more!
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It may be non-obvious but the WebAssembly Garbage Collection proposal together with StringRef is key to enabling efficient sharing of structured data between WebAssembly & JavaScript ⚡
In time, the immense value of this work to the web platform will become apparent 🔥
This is a nuanced and ground breaking change. Efficient string sharing between host VM and WASM is a game changer for many use cases.
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Many exciting items on this week's
@TC39
meeting agenda 😉
🔸Async Context
🔸Async Explicit Resource Mgmt
🔸Decimal
🔸Decorator Metadata & Method Params
🔸Import Assertions/Reflection
🔸Iterator.range & Helpers
🔸Promise.withResolvers
🔸Type Annotations
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Last week
@MylesBorins
successfully pushed Top-Level Await to Stage 3 at TC39 🚀
I'd like to say thank you for the input from the JS tooling community on this proposal.
TLA is a widely demanded feature that allows you to await promises from outside of functions.
(1/n)
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ECMAScript excitement 😉
Stage 3 TC39 Private Instance Fields has landed in upstream TypeScript. Heading for TypeScript 3.8!
Congrats to
@maxheiber
@joeywatts96
Michael Gunter, Ravi Amin, Michael Molisani
@jbhoosreddy
@drosenwasser
@sanders_n
@rbuckton
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ECMAScript excitement 😉
@jackworks_asref
is brewing a new TC39 proposal (Stage-0) to bring `enum` to JavaScript 🎉
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Import Maps have now been implemented in all major browsers & engines 🔥
🔸 Chromium 89
🔸 Firefox 108
🔸 Safari 16.4 Beta
This lets browsers understand code that contains:
import _ from "lodash"
📜 This article by Yoshi explains what they are & the problem they solve.
Late last year, we implemented the Import Maps specification in Firefox. Yoshi (the engineer working on it) wrote an in-depth introduction to it, along with a deep dive that you can expect next week!
Read the blog post here:
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Typescript 5.0 is released 🎉
So many new features, including...
🔷 ES Decorators
🔷 --moduleResolution bundler matches semantics used by Vite et al
🔷 --allowImportingTsExtensions allows referencing *.ts files 👍
🔷 --allowArbitraryExtensions means app.css gets app.d.css.ts
TypeScript 5.0 is here! 🎉🎉
Learn about what's new and try it today!
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Deno contains a single version of TypeScript.
TypeScript checking gets better over time, meaning source code fixes are needed to work with new versions.
Is the expectation that all Deno packages should be fixed up when Deno bumps its TypeScript version?
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ECMAScript excitement 😉
Congrats to Justin Ridgewell
@vercel
&
@legendecas
on advancing the "Async Context" proposal to Stage 1 at
@TC39
today 🎉
AsyncContext lets you propagate state throughout a potentially async callstack.
It is similar to Node's AsyncLocalStorage 👍
We've got AsyncContext for JavaScript accepted as a TC39 stage 1 proposal 🥳: (Great thanks to Justin Ridgewell!!)
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ECMAScript excitement 😉
Congrats to champions
@littledan
@apaprocki
on advancing the TC39 proposal for Decimal numbers to Stage 1.
0.1m + 0.2m === 0.3m // true!
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ECMAScript excitement 😉
Congrats to
@caio_nepo
on advancing all three Class Fields proposals to Stage 4 at TC39 🎉
Thanks to champion
@littledan
and the many **many** contributors who came together to make this happen. It has been an epic joint effort over several years.
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📜 The Future of TypeScript with
@drosenwasser
🔹 Delivered in 2023: Decorators, `using`, IDE delights, TypeChat
🔹 Priority for 2024: Speed
🔹 Biggest change coming: Isolated Declarations for parallel builds
🔹 Prepare for: TS5.5 deprecations
🔹 Most demanded: No build step 👍
Daniel Rosenwasser on TypeScript and What’s Ahead in 2024
@lorainelawson
@drosenwasser
@TypeScript
#microsoft
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Shipping in all major browsers 👍
Promise.withResolvers() has hit Stage 4, is in Chrome+FF, and is easy to polyfill.
This is really handy for situations where you don't want to pass work into a Promise, but instead pass around the resolve/reject methods.
Super handy for callback and stream based APIs
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ECMAScript excitement 😉
Congrats to
@leobalter
on advancing ShadowRealm to Stage 2.7
@TC39
today 🎉
(Read below for more on Stage 2.7 🧵)
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tsimp lets Node run TypeScript files directly 👍
💯 Uses the genuine tsc compiler
⚡ Blazing fast due to caching
✅ Includes type-checking
🆕 Works with Node 20.6 --import
Here's the conclusion of this thread, a TypeScript --import module loader with the full power of TSC's type checking, and (warm cache) performance as good as or better than "blazing fast" ts compilers written in Rust and Golang (which don't typecheck).
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@mattpocockuk
I always preferred using DTS files to express type-only modules as it felt like it better conveyed intent.
However
@atcb
helpfully explained TypeScript doesn't truly support this usage pattern and so the guidance today is to use TS files.
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TypeScript 5.3 RC 🎉
🔶 JS: Import Attributes
🔷 Modules: "resolution-mode" for type-only imports
🔷 Checking: Narrowing of boolean comparison, switch(true), instanceof-via-hasInstance
🔷 Checking: Strict `super` access
🔷 Perf: Faster *.ts parsing
🔷 npm: 20% smaller package
The release candidate of TypeScript 5.3 is out - we're looking for feedback to make sure this release is as perfect as possible!
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TypeScript 5.4 Beta is out 🎉
🔶 JS: Object.groupBy & Map.groupBy
🔷 Checking: Closure bindings narrowed after final assignment
🔷 Checking: "NoInfer" utility type
🔷 Checking: Customizable Import Attributes
🔷 Modules: require() in ESM for Bun
🔷 IDE: Quick fix missing params
TypeScript 5.4 Beta is available to try! This release has lots of type narrowing improvements, the 'NoInfer' type helper, groupBy, better options for bundlers, and more!
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⚡️ Do you enjoy making JavaScript / C++ systems go fast?
I'm looking for a Performance Engineer to help make the
@TheTerminal
even faster 🔥
Tech stack spans
@nodejs
, Chromium,
@SpiderMonkeyJS
,
@electronjs
with upstream contributions encouraged & supported by the
@business
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Node excitement 😉
Congrats to
@JoyeeCheung
at
@igalia
on landing **experimental** support for require(ESM) in Node 🎉
The intent is to allow more CommonJS packages to migrate to ESM without breaking compatibility. This should help eliminate the [ERR_REQUIRE_ESM] error 👍
Landed experimental support for synchronous require(esm) to load ES modules without top-level await 🥳
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TypeScript 5.4 RC is out 🎉
🔶 JS: Object.groupBy & Map.groupBy
🔷 Checking: Closure bindings narrowed after final assignment
🔷 Checking: "NoInfer" utility type
🔷 Checking: Customizable Import Attributes
🔷 Modules: require() in ESM for Bun
🔷 IDE: Quick fix missing params
The release candidate of TypeScript 5.4 is now ready to download!
Read up on what's coming in TypeScript 5.4 👀
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Lots of goodness in TypeScript 4.5 👍
🔥 Node ESM (type: module + package imports/exports + .mjs/.cjs)
🔥 `type` keyword on import specifiers
🔥 Private Field Presence Checks thanks to
@acutmore
🔥 Import Assertions for importing JSON modules
🔥 `Awaited` type
Happy birthday to us! 🎂 What better way to celebrate 9 years of being public than a beta release?
Try out TypeScript 4.5 beta! Now bringing great new features including better support for ES modules in Node.js.
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ECMAScript excitement 😉
Safari 17.4 brings:
🔶 Object.groupBy & Map.groupBy
🔶 Promise.withResolvers
🔶 ArrayBuffer methods: detached(), transfer(), transferToFixedLength()
🔶 Intl.DateTimeFormat supports TimeZoneOffset format
Safari 17.4 beta is out ! So much in it, including:
- @scope
- align-content on blocks
- vertical form controls
- <hr> inside <select>
- <input type="checkbox" switch>
- VP8/VP9 & WebM on iOS & iPadOS
- Vorbis audio codec on iOS
- Fullscreen API on iOS
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