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Overview

TC39 proposals

Section titled “TC39 proposals”

Stage 4 • 0%

Section titled “Stage 4 • ”
Feature Type CoreJS Babel Civet JS+
Temporal Polyfill ❌ ❌ ❌ ❌

Stage 3 • 10%

Section titled “Stage 3 • ”
Feature Type CoreJS Babel Civet JS+
Atomics.pause Polyfill ❌ ❌ ❌ ❌
Decorators Syntax ✅ ✅ ❌ ✅
Eval checks Runtime ❌ ❌ ❌
Import defer Syntax ❌ ❌ ❌
Import text Runtime ❌
Joint iteration Polyfill ✅ ❌ ❌ ❌
Legacy RegExp features Polyfill ❌ ❌ ❌ ❌
Non-extensible applies to private Runtime ❌ ❌ ❌
Source phase imports Runtime ✅ ❌ ❌
Using Syntax ❌ ❌ ❌

Stage 2.7 • 22%

Section titled “Stage 2.7 • ”
Feature Type CoreJS Babel Civet JS+
Error stack accessor Polyfill ❌
ESM module phase imports (workers import defer) Runtime ❌
Immutable ArrayBuffers Runtime ❌
Import bytes Syntax ❌
Iterator chunking Polyfill ✅ ❌ ❌ ✅
Iterator join Polyfill ❌
Iterator.includes Polyfill ❌ ❌ ❌ ❌
Promise await dictionary Polyfill ❌ ❌ ❌ ✅
ShadowRealm Polyfill ❌

Stage 2 • 21%

Section titled “Stage 2 • ”
Feature Type CoreJS Babel Civet JS+
Async context Polyfill ❌
Async iterator helpers Polyfill ✅ ❌
Collection (coerceKey, coerceValue) Polyfill ❌
Curtailing the power of "Thenables" Polyfill ❌
Deferred re-exports (export defer) Syntax ❌
Destructuring private Syntax ❌
Discard binding Syntax ✅ ❌ ✅
Error.captureStackTrace Polyfill ❌
Extractors Syntax ✅ ❌
Function implementation hiding proposal (hide source directive) Syntax ❌
Function sent Syntax ✅ ❌
Import sync Syntax ❌
Iterator range (range) Polyfill ✅ ❌
Jobcallback module Runtime ❌
JSON.parseImmutable Polyfill ❌
Math.clamp Polyfill ✅ ❌ ❌ ✅
Module declarations (module blocks) Syntax ✅ ❌
Module expressions Runtime ❌
Object.keysLength Polyfill ❌ ❌ ❌ ✅
Pipeline operator Syntax ✅ ✅ ✅
Promise.isPromise Polyfill ❌ ❌ ❌ ✅
Reflect.isTemplateObject Polyfill ✅ ❌
RegExp buffer boundaries Syntax ❌
Seeded pseudo random numbers Syntax ❌
String dedent Runtime ✅ ✅ ❌
Structs Syntax ❌
Symbol predicates Polyfill ✅ ❌
Throw expressions Syntax ✅ ❌ ✅

Stage 1 • 3%

Section titled “Stage 1 • ”
Feature Type CoreJS Babel Civet JS+
{BigInt,Number}.fromString Polyfill ✅ ❌
Alias accessors (alias) Syntax ❌
Array Equality Polyfill ❌
Array filtering Polyfill ✅ ❌
Array.prototype.unique() Polyfill ✅ ❌
Array.zip and Array.zipKeyed Polyfill ❌
Asset References ❌
Async initialization ❌
await operations ❌
BigInt Math ❌
Binary AST Runtime ❌
Block Params ❌
Built In Modules (aka JS Standard Library) Polyfill ❌
Bulk-add array elements Polyfill ❌
Call-this operator ❌
Cancellation API Polyfill ❌
Change Number.parseInt/parseFloat not to coerce null/undefined/NaN Runtime ❌
class Access Expressions ❌
Class Brand Checks ❌
Class Method Parameter Decorators ❌
Collection methods Polyfill ✅ ❌
Collections of/from Polyfill ✅ ❌
Compare strings by codepoint Runtime ✅ ❌
Compartments Runtime ❌
Composable accessors (@memoized, @validate, @normalize) Syntax ❌
Composites Polyfill ❌
Concurrency Control ❌
Cryptographically Secure Random Number Generation ❌
DataView get/set Uint8Clamped methods ✅ ❌
Date.parse uniform parsing Runtime ❌
Decimal Syntax ❌
Declarations in Conditionals ❌
Deep Path Properties in Record Literals ❌
Disposable AsyncContext.Variable ❌
Double-Ended Iterator and Destructuring ❌
Dynamic Modules ❌
Emitter ❌
Enums Syntax ❌
Error frames above Polyfill ❌
Error option limit Polyfill ❌
Error stacks ❌
Export default from Syntax ✅ ❌ ✅
Extensions ❌
Faster Promise adoption ❌
First-class protocols ❌
Freezing prototypes ❌
Function and Object Literal Decorators ❌
Function Memoization Runtime ❌
Function once ❌
Get Intrinsic ❌
Grouped Accessors and Auto-Accessors ❌
IDL for ECMAScript ❌
Improved Escapes for Template Literals ❌
Inspector Runtime ❌
Iterator unique ❌
Legacy reflection features for functions in JavaScript ❌
Limited ArrayBuffer ❌
Locale Extensions ❌
Mass Proxy Revocation ❌
Maximally minimal mixins ❌
Module Global ❌
Module Keys ❌
Module sync assert ❌
Modulus and Additional Integer Math ❌
Negated in and instanceof operators Syntax ❌
new.initialize Polyfill ❌
Object pick/omit Polyfill ❌
Object property count Polyfill ❌ ❌ ❌ ✅
Object.freeze + Object.seal syntax Polyfill ❌
Object.getNonIndexStringProperties() Polyfill ❌
Observable Polyfill ✅ ❌
OOM Fails Fast ❌
Optional chaining in assignment LHS ❌
Partial application Syntax ✅ ❌
Pattern matching (match) Syntax ✅ ✅ ❌
Policy Maps and Sets ❌
Preserve Host Virtualizability ❌
Private declarations ❌
Prototype pollution mitigation ❌
Random Polyfill ❌ ❌ ❌ ✅
Readonly Collections ❌
RegExp \R Escape Syntax ❌
RegExp Atomic Operators Syntax ❌
RegExp Extended Mode and Comments ❌
Representing amounts Polyfill ❌
Restrict subclassing support in built-in methods ❌
Reverse iteration ❌
Reversible string split ❌
Richer Keys (compositeKey, compositeSymbol) Polyfill ✅ ❌
Secure ES Runtime ❌
Signals Polyfill ❌
Slice notation Syntax ❌
Stabilize ❌
Stable Formatting ❌
Standardized Debug ❌
Strict Enforcement of 'using' ❌
String.cooked Polyfill ✅ ❌
String.prototype.codePoints Polyfill ❌
Support for Distributed Promise Pipelining ❌
Type annotations Syntax ❌
TypedArray concat Polyfill ❌
TypedArray find within Polyfill ❌
Unordered Async Iterator Helpers ❌
Wavy Dot: Syntactic Support for Promise Pipelining ❌

Stage 0 • 12%

Section titled “Stage 0 • ”
Feature Type CoreJS Babel Civet JS+
Additional metaproperties ❌
as destructuring patterns Syntax ❌
Async do expressions Syntax ✅ ✅ ✅
Catch Guard ❌
Defensible Classes ❌
Do expressions Syntax ✅ ✅ ✅
Function bind syntax (::) Syntax ✅ ❌
Function expression decorators ❌
Function.prototype.demethodize Polyfill ✅ ❌
Method parameter decorators ❌
Nested import declarations ❌
Object Shorthand Improvements ❌
Orthogonal Classes ❌
Reflect.{isCallable,isConstructor} Polyfill ✅ ❌
Relationships ❌
String trim characters ❌
Structured Clone ❌

Stage inactive • %

Section titled “Stage inactive • ”
Feature Type CoreJS Babel Civet JS+
{Set,Map}.prototype.toJSON Polyfill ❌
%constructor%.construct ❌
Annex B — HTML Attribute Event Handlers ❌
ArrayBuffer.prototype.transfer Polyfill ❌
Blöcks ❌
Builtins.typeOf() and Builtins.is() Polyfill ❌
Callable class constructors ❌
Cancelable Promises ❌
Date.parse fallback semantics Runtime ❌
deprecated Syntax ❌
Distinguishing literal strings ❌
Dynamic import host adjustment Runtime ❌
Dynamic Module Reform ❌
Extensible numeric literals ❌
from ... import Syntax ❌
Function helpers ❌
Function.pipe and flow ❌
Generator arrow functions ❌
Generic Comparison ❌
Improving iteration on Objects ❌
JSON.tryParse ❌
Math Extensions Polyfill ❌
Math.signbit: IEEE-754 sign bit Polyfill ❌
Negative array subscript Runtime ❌ ❌ ✅
Normative ICU Reference ❌
Object enumerables ❌
Object.shallowEqual ❌
Operator overloading ❌
Proposed Grammar change to ES Modules ❌
Record & Tuple ❌
RefCollection ❌
RegExp Atomic Groups & Possessive Quantifiers ❌
Sequence properties in Unicode property escapes ❌
SIMD.JS - SIMD APIs ❌
String.prototype.at Syntax ❌
Symbol.thenable Polyfill ❌
Tagged Collection Literals ❌
Typed Objects ❌
TypedArray stride parameter ❌
Typeof null operator Runtime ❌ ❌ ✅
Unused Function Parameters ❌
Updates to Tail Calls to include an explicit syntactic opt-in ❌
use module Syntax ❌
UUID ❌
WeakRefs cleanupSome ❌
Zones ❌

Resources

Section titled “Resources”
Section titled “Related”