Survey and analysis of TC39 proposals by nature

ECMA262 proposal summary.md

Totals

Proposals by acceptance status

Status	Syntactic only	Any Syntactic	Total	Any Semantic	Semantic only
Stage 4	6 (10.2%)	27 (45.8%)	59	53 (89.8%)	32 (54.2%)
Stage 3	0 (0%)	9 (60%)	15	15 (100%)	6 (40%)
Stage 2.7	0 (0%)	0 (0%)	3	3 (100%)	3 (100%)
Stage 2	0 (0%)	10 (41.7%)	24	24 (100%)	14 (58.3%)
Total 2+	7 (6.9%)	46 (45.5%)	101	94 (93.1%)	55 (54.5%)
Total	32 (12.7%)	117 (46.4%)	252	220 (87.3%)	135 (53.6%)
Total 1-	25 (16.6%)	71 (47%)	151	126 (83.4%)	80 (53%)
Stage 1	14 (14.9%)	43 (45.7%)	94	80 (85.1%)	51 (54.3%)
Stage 0	3 (20%)	10 (66.7%)	15	12 (80%)	5 (33.3%)
Inactive	8 (19%)	18 (42.9%)	42	34 (81%)	24 (57.1%)

Proposals by nature

Natures	Stage 4	Stage 3	Stage 2.7	Stage 2	Stage 1	Stage 0	Inactive	Total 2+	Total 1-	Total
Syntactic only	6 (19.4%)	0 (0)	0 (0%)	0 (0%)	14 (45.2%)	3 (9.7%)	8 (25.8%)	6 (19.4%)	25 (80.6%)	31
Semantic only	32 (23.7%)	6 (4.4%)	3 (2.2%)	14 (10.4%)	51 (37.8%)	5 (3.7%)	24 (17.8%)	55 (40.7%)	80 (59.3%)	135
Syntactic + Semantic	21 (24.4%)	9 (10.5%)	0 (0%)	10 (11.6%)	29 (33.7%)	7 (8.1%)	10 (11.6%)	40 (46.5%)	46 (53.5%)	86
Any Syntactic	28 (23.9%)	9 (7.7%)	0 (0%)	10 (8.5%)	43 (36.8%)	10 (8.5%)	18 (15.4%)	47 (40.2%)	71 (60.7%)	117
Any Semantic	53 (24.0%)	15 (6.8%)	3 (1.4%)	24 (10.9%)	80 (36.2%)	12 (5.4%)	34 (15.4%)	95 (43.0%)	126 (57.0%)	221
Any	59 (23.4%)	15 (6%)	3 (1.2%)	24 (9.5%)	94 (37.3%)	15 (6%)	42 (16.7%)	101 (40.1%)	151 (59.9%)	252

Successful proposals.md

Finished Proposals

Finished proposals are proposals that have reached stage 4, and are included in the latest draft of the specification.

Syntactic	Semantic	Proposal	Author	Champion(s)	TC39 meeting notes	Expected Publication Year
	✓	Array.prototype.includes	Domenic Denicola	Domenic Denicola Rick Waldron	November 2015	2016
✓	✓	Exponentiation operator	Rick Waldron	Rick Waldron	January 2016	2016
	✓	Object.values/Object.entries	Jordan Harband	Jordan Harband	March 2016	2017
	✓	String padding	Jordan Harband	Jordan Harband Rick Waldron	May 2016	2017
	✓	Object.getOwnPropertyDescriptors	Jordan Harband Andrea Giammarchi	Jordan Harband Andrea Giammarchi	May 2016	2017
✓		Trailing commas in function parameter lists and calls	Jeff Morrison	Jeff Morrison	July 2016	2017
✓	✓	Async functions	Brian Terlson	Brian Terlson	July 2016	2017
	✓	Shared memory and atomics	Lars T Hansen	Lars T Hansen	January 2017	2017
✓		Lifting template literal restriction	Tim Disney	Tim Disney	March 2017	2018
✓	✓	s (dotAll) flag for regular expressions	Mathias Bynens	Brian Terlson Mathias Bynens	November 2017	2018
✓	✓	RegExp named capture groups	Gorkem Yakin Daniel Ehrenberg	Daniel Ehrenberg Brian Terlson Mathias Bynens	November 2017	2018
✓	✓	Rest/Spread Properties	Sebastian Markbåge	Sebastian Markbåge	January 2018	2018
✓	✓	RegExp Lookbehind Assertions	Gorkem Yakin Nozomu Katō Daniel Ehrenberg	Daniel Ehrenberg Mathias Bynens	January 2018	2018
✓	✓	RegExp Unicode Property Escapes	Mathias Bynens	Brian Terlson Daniel Ehrenberg Mathias Bynens	January 2018	2018
	✓	Promise.prototype.finally	Jordan Harband	Jordan Harband	January 2018	2018
✓	✓	Asynchronous Iteration	Domenic Denicola	Domenic Denicola	January 2018	2018
✓		Optional catch binding	Michael Ficarra	Michael Ficarra	May 2018	2019
✓		JSON superset	Richard Gibson	Mark Miller Mathias Bynens	May 2018	2019
	✓	Symbol.prototype.description	Michael Ficarra	Michael Ficarra	November 2018	2019
	✓	Function.prototype.toString revision	Michael Ficarra	Michael Ficarra	November 2018	2019
	✓	Object.fromEntries	Darien Maillet Valentine	Jordan Harband Kevin Gibbons	January 2019	2019
	✓	Well-formed JSON.stringify	Richard Gibson	Mathias Bynens	January 2019	2019
	✓	String.prototype.{trimStart,trimEnd}	Sebastian Markbåge	Sebastian Markbåge Mathias Bynens	January 2019	2019
	✓	Array.prototype.{flat,flatMap}	Brian Terlson Michael Ficarra Mathias Bynens	Brian Terlson Michael Ficarra	January 2019	2019
	✓	String.prototype.matchAll	Jordan Harband	Jordan Harband	March 2019	2020
	✓	import()	Domenic Denicola	Domenic Denicola	June 2019	2020
✓	✓	BigInt	Daniel Ehrenberg	Daniel Ehrenberg	June 2019	2020
	✓	Promise.allSettled	Jason Williams Robert Pamely Mathias Bynens	Mathias Bynens	July 2019	2020
	✓	globalThis	Jordan Harband	Jordan Harband	October 2019	2020
✓	✓	for-in mechanics	Kevin Gibbons	Kevin Gibbons	December 2019	2020
✓	✓	Optional Chaining	Gabriel Isenberg Claude Pache Dustin Savery	Gabriel Isenberg Dustin Savery Justin Ridgewell Daniel Rosenwasser	December 2019	2020
✓	✓	Nullish coalescing Operator	Gabriel Isenberg	Gabriel Isenberg Justin Ridgewell Daniel Rosenwasser	December 2019	2020
✓	✓	import.meta	Domenic Denicola	Gus Caplan	March 2020	2020
	✓	String.prototype.replaceAll	Peter Marshall Jakob Gruber Mathias Bynens	Mathias Bynens	June 2020	2021
	✓	Promise.any	Mathias Bynens Kevin Gibbons Sergey Rubanov	Mathias Bynens	July 2020	2021
	✓	WeakRefs	Dean Tribble Sathya Gunasekaran	Dean Tribble Mark Miller Till Schneidereit Sathya Gunasekaran Daniel Ehrenberg	July 2020	2021
✓	✓	Logical Assignment Operators	Justin Ridgewell	Justin Ridgewell Hemanth HM	July 2020	2021
✓		Numeric separators	Sam Goto Rick Waldron	Sam Goto Rick Waldron Leo Balter	July 2020	2021
✓	✓	Class Fields (Private instance methods and accessors, Class Public Instance Fields & Private Instance Fields, Static class fields and private static methods)	Daniel Ehrenberg	Daniel Ehrenberg Kevin Gibbons	April 2021	2022
✓	✓	RegExp Match Indices	Ron Buckton	Ron Buckton	May 2021	2022
✓	✓	Top-level await	Myles Borins Yulia Startsev Daniel Ehrenberg Guy Bedford Ms2ger	Myles Borins Yulia Startsev	May 2021	2022
✓	✓	Ergonomic brand checks for Private Fields	Jordan Harband	Jordan Harband	July 2021	2022
	✓	.at()	Shu-yu Guo Tab Atkins	Shu-yu Guo Tab Atkins	August 2021	2022
	✓	Accessible Object.prototype.hasOwnProperty	Jamie Kyle	Tierney Cyren Jamie Kyle	August 2021	2022
✓	✓	Class Static Block	Ron Buckton	Ron Buckton	August 2021	2022
	✓	Error Cause	Chengzhong Wu	Chengzhong Wu Hemanth HM	October 2021	2022
	✓	Array find from last	Wenlu Wang	Wenlu Wang Daniel Rosenwasser	June 2022	2023
✓		Hashbang Grammar	Bradley Farias	Bradley Farias	July 2022	2023
	✓	Symbols as WeakMap keys	Daniel Ehrenberg Richard Button Robin Ricard Leo Balter Rick Waldron Caridy Patiño	Daniel Ehrenberg Richard Button Robin Ricard Leo Balter Rick Waldron Caridy Patiño	January 2023	2023
	✓	Change Array by Copy	Ashley Claymore Robin Ricard	Ashley Claymore Robin Ricard	March 2022	2023
	✓	Well-Formed Unicode Strings	Guy Bedford Bradley Farias	Guy Bedford Bradley Farias Michael Ficarra	May 2023	2024
	✓	Atomics.waitAsync	Lars Hansen	Shu-yu Guo Lars Hansen	May 2023	2024
✓	✓	RegExp v flag with set notation + properties of strings	Markus Scherer Mathias Bynens	Mathias Bynens	May 2023	2024
	✓	Resizable and growable ArrayBuffers	Shu-yu Guo	Shu-yu Guo	September 2023	2024
	✓	Array Grouping	Justin Ridgewell	Justin Ridgewell Jordan Harband	November 2023	2024
	✓	Promise.withResolvers	Peter Klecha	Peter Klecha	November 2023	2024
	✓	ArrayBuffer transfer	Shu-yu Guo Jordan Harband Yagiz Nizipli	Shu-yu Guo Jordan Harband Yagiz Nizipli	February 2024	2024
✓	✓	Duplicate named capture groups	Kevin Gibbons	Kevin Gibbons	April 2024	2025
	✓	New Set methods	Michał Wadas Sathya Gunasekaran Kevin Gibbons	Kevin Gibbons	April 2024	2025
27/59	53/59

See also the active proposals, stage 1 proposals, stage 0 proposals, and inactive proposals documents.

Stage 3

Syntactic	Semantic	Proposal	Author	Champion	Test262 Feature Flag	Last Presented
✓	✓	Legacy RegExp features in JavaScript	Claude Pache	Mark Miller Claude Pache	legacy-regexp	May 2017
✓	✓	JSON Modules	Myles Borins Sven Sauleau Dan Clark Daniel Ehrenberg	Myles Borins Sven Sauleau Dan Clark Daniel Ehrenberg	json-modules	January 2021
	✓	Temporal	Philipp Dunkel Maggie Johnson-Pint Matt Johnson-Pint Brian Terlson Shane Carr Ujjwal Sharma Philip Chimento Jason Williams Justin Grant	Philipp Dunkel Maggie Johnson-Pint Matt Johnson-Pint Brian Terlson Shane Carr Ujjwal Sharma Philip Chimento Jason Williams Justin Grant	Temporal	March 2021
✓	✓	Decorators	Daniel Ehrenberg Kristen Hewell Garrett	Kristen Hewell Garrett	decorators	March 2023
	✓	JSON.parse source text access	Richard Gibson	Richard Gibson	json-parse-with-source	January 2023
✓	✓	RegExp Modifiers	Ron Buckton	Ron Buckton	regexp-modifiers	June 2022
	✓	Array.fromAsync	J.S. Choi	J.S. Choi	Array.fromAsync	May 2023
	✓	Sync Iterator helpers	Gus Caplan	Michael Ficarra Jonathan Keslin Kevin Gibbons	iterator-helpers	November 2022
✓	✓	Explicit Resource Management	Ron Buckton	Ron Buckton	explicit-resource-management	March 2023
	✓	Float16 on TypedArrays, DataView, Math.f16round	Leo Balter	Leo Balter Kevin Gibbons	❓	May 2023
✓	✓	Decorator Metadata	Kristen Hewell Garrett	Kristen Hewell Garrett	❓	May 2023
✓	✓	Import Attributes	Myles Borins Sven Sauleau Dan Clark Daniel Ehrenberg	Sven Sauleau Dan Clark Daniel Ehrenberg Nicolò Ribaudo	import-attributes	March 2023
✓	✓	Source Phase Imports	Luca Casonato	Guy Bedford Luca Casonato	❓	July 2023
	✓	Uint8Array to/from Base64	Kevin Gibbons	Kevin Gibbons	❓	February 2024
✓	✓	Dynamic Code Brand Checks	Nicolo Ribaudo	Krzysztof Kotowicz Mike Samuel</br />Nicolo Ribaudo	❓	April 2024
9/15	15/15

Stage 2.7

Syntactic	Semantic	Proposal	Author	Champion	Test262 Feature Flag	Last Presented
	✓	ShadowRealm	Caridy Patiño Jean-Francois Paradis	Dave Herman Mark Miller Caridy Patiño Leo Balter Rick Waldron Chengzhong Wu	ShadowRealm	February 2024
	✓	Promise.try	Jordan Harband	Jordan Harband		April 2024
	✓	Math.sumPrecise	Kevin Gibbons	Kevin Gibbons		April 2024
0/3	3/3

Stage 2

Syntactic	Semantic	Proposal	Author	Champion	Last Presented
✓	✓	function.sent metaproperty	Allen Wirfs-Brock	HE Shi-Jun	July 2019
✓	✓	throw expressions	Ron Buckton	Ron Buckton	January 2018
✓	✓	Function implementation hiding	Domenic Denicola Michael Ficarra	Michael Ficarra	June 2020
	✓	collection normalization	Bradley Farias	Bradley Farias	January 2019
	✓	Array.isTemplateObject	Mike Samuel, Krzysztof Kotowicz	Krzysztof Kotowicz	December 2019
	✓	Map.prototype.emplace	Bradley Farias	Erica Pramer	July 2020
	✓	Dynamic Import Host Adjustment	Mike Samuel, Krzysztof Kotowicz	Krzysztof Kotowicz	December 2019
✓	✓	Record & Tuple	Robin Ricard Richard Button	Robin Ricard Richard Button	December 2021
✓	✓	Module Expressions	Surma Daniel Ehrenberg Nicolò Ribaudo	Surma Nicolò Ribaudo	November 2022
✓	✓	Pipeline Operator	J. S. Choi James DiGioia Ron Buckton Tab Atkins	J. S. Choi Ron Buckton Tab Atkins	August 2021
✓	✓	Destructure Private Fields	Justin Ridgewell	Justin Ridgewell	December 2021
✓	✓	RegExp Buffer Boundaries (\A, \z, \Z)	Ron Buckton	Ron Buckton	December 2021
	✓	String.dedent	Misha Kaletsky Hemanth HM Justin Ridgewell	Hemanth HM Justin Ridgewell	June 2022
	✓	JSON.parseImmutable	Robin Ricard Richard Button Nicolò Ribaudo Ashley Claymore	Robin Ricard Richard Button Nicolò Ribaudo Ashley Claymore	July 2022
✓	✓	Module Declarations	Daniel Ehrenberg Nicolò Ribaudo	Daniel Ehrenberg Mark Miller Nicolò Ribaudo	November 2022
	✓	Symbol Predicates	Robin Ricard Jordan Harband	Ashley Claymore Jordan Harband	January 2023
	✓	Async Iterator helpers	Gus Caplan	Michael Ficarra Jonathan Keslin Kevin Gibbons	January 2023
	✓	Iterator.range	Jack Works	Jack Works	March 2023
	✓	Async Context	Chengzhong Wu	Chengzhong Wu Justin Ridgewell	March 2023
	✓	Time Zone Canonicalization	Justin Grant	Justin Grant Richard Gibson	May 2023
✓	✓	Deferring Module Evaluation	Yulia Startsev Guy Bedford	Yulia Startsev Guy Bedford Nicolò Ribaudo	July 2023
	✓	RegExp.escape	Domenic Denicola Benjamin Gruenbaum Jordan Harband	Jordan Harband Kevin Gibbons	September 2023
	✓	Joint Iteration	Michael Ficarra	Michael Ficarra	February 2024
	✓	Redeclarable global eval-introduced vars	Shu-yu Guo	Shu-yu Guo	February 2024
10/24	24/24

Unsuccessful proposals.md

Stage 1 Proposals

Stage 1 proposals represent problems that the committee is interested in spending time exploring solutions to.

Proposals follow this process document.

Syntactic	Semantic	Proposal	Author	Champion	Last Presented
✓		export v from "mod"; statements	Lee Byron	Ben Newman John-David Dalton	July 2017
	✓	Observable	Jafar Husain	Jafar Husain Mark Miller	May 2017
	✓	SES (Secure EcmaScript)	Mark Miller Chip Morningstar Caridy Patiño	Mark Miller Chip Morningstar Caridy Patiño	February 2020
	✓	of and from on collection constructors	Leo Balter	Leo Balter	September 2016
	✓	Error stacks	Jordan Harband Mark Miller	Jordan Harband Mark Miller	January 2017
✓	✓	do expressions	Dave Herman	Kevin Gibbons	June 2020
	✓	Change Number.parseInt/parseFloat to not coerce null/undefined/NaN (repo link TBD)		Brendan Eich	July 2017
✓		Binary AST	Shu-yu Guo	Shu-yu Guo	May 2018
✓	✓	First-class protocols	Michael Ficarra	Michael Ficarra	July 2018
✓	✓	Partial application	Ron Buckton	Ron Buckton	July 2018
	✓	Cancellation API	Ron Buckton	Ron Buckton Brian Terlson	July 2018
	✓	String.prototype.codePoints	Ingvar Stepanyan	Mathias Bynens	May 2018
✓	✓	Object.freeze + Object.seal syntax	Keith Cirkel	Keith Cirkel	November 2017
✓		Block Params	Sam Goto	Sam Goto	November 2017
	✓	{BigInt,Number}.fromString	Mathias Bynens	Mathias Bynens	January 2018
	✓	Math.seededRandoms()	Tab Atkins	Tab Atkins	January 2018
✓		Maximally minimal mixins	Justin Fagnani	Justin Fagnani	January 2018
	✓	Collection methods	Michał Wadas	Sathya Gunasekaran	January 2018
	✓	Richer Keys	Bradley Farias	Bradley Farias	January 2019
✓		Slice notation	Sathya Gunasekaran	Sathya Gunasekaran	July 2020
✓	✓	Module Keys	Mike Samuel	Mike Samuel	May 2018
✓	✓	class Access Expressions	Ron Buckton	Ron Buckton	September 2020
✓	✓	Pattern Matching	Jordan Harband Mark Cohen Tab Atkins Daniel Rosenwasser Jack Works Ross Kirsling	Jordan Harband Mark Cohen Tab Atkins Daniel Rosenwasser Jack Works Ross Kirsling	March 2022
✓	✓	Dynamic Modules	Bradley Farias	Bradley Farias	July 2018
	✓	Built In Modules (aka JS Standard Library)	Michael Saboff Mattijs Hoitink	Michael Saboff Mattijs Hoitink Mark Miller	September 2020
	✓	uniform parsing of quasi-standard Date.parse input	Richard Gibson	Richard Gibson	September 2018
	✓	IDL for ECMAScript	Daniel Ehrenberg	Daniel Ehrenberg	September 2018
✓	✓	Asset References	Sebastian Markbage	Sebastian Markbage	November 2018
	✓	Freezing prototypes	Kevin Gibbons	Kevin Gibbons	January 2019
✓	✓	new.initialize	Daniel Ehrenberg	Daniel Ehrenberg	January 2019
✓	✓	Private declarations	Justin Ridgewell	Justin Ridgewell	March 2019
	✓	Emitter	Shu-yu Guo Pedram Emrouznejad	Shu-yu Guo Pedram Emrouznejad	June 2019
	✓	Reverse iteration	Leo Balter Jordan Harband	Leo Balter Jordan Harband	July 2019
✓	✓	Declarations in Conditionals	Devin Rousso	Devin Rousso	October 2019
	✓	UUID	Benjamin Coe Robert Kieffer Christoph Tavan	Benjamin Coe	October 2019
	✓	Readonly Collections	Mark Miller Peter Hoddie	Mark Miller Peter Hoddie	October 2019
	✓	Support for Distributed Promise Pipelining	Mark Miller Chip Morningstar Michael Fig	Mark Miller Chip Morningstar Michael Fig	October 2019
✓		Wavy Dot: Syntactic Support for Promise Pipelining	Mark Miller Chip Morningstar Michael Fig	Mark Miller Chip Morningstar Michael Fig	December 2019
	✓	OOM Fails Fast	Mark Miller	Mark Miller	December 2019
	✓	Array filtering	Justin Ridgewell	Justin Ridgewell	February 2020
	✓	Async initialization	Bradley Farias	Bradley Farias	February 2020
	✓	Decimal	Daniel Ehrenberg Andrew Paprocki	Philip Chimento Andrew Paprocki Jesse Alama	December 2021
	✓	Preserve Host Virtualizability	Mark Miller J.F. Paradis Caridy Patiño Dan Finley Alan Schmitt	Mark Miller J.F. Paradis Caridy Patiño Dan Finley Alan Schmitt	February 2020
	✓	Legacy reflection features for functions in JavaScript	Mark Miller Claude Pache Jack Works	Mark Miller Claude Pache Jack Works	February 2020
	✓	Cryptographically Secure Random Number Generation	Ron Buckton	Ron Buckton	February 2020
	✓	Compartments	Bradley Farias	Bradley Farias Mark S. Miller Caridy Patiño J.F. Paradis Patrick Soquet Kris Kowal	March 2020
✓	✓	Deep Path Properties in Record Literals	Rick Button	Rick Button	June 2020
	✓	Restrict subclassing support in built-in methods	Yulia Startsev Shu-yu Guo	Yulia Startsev Shu-yu Guo	June 2020
	✓	Array Equality	Hemanth HM Jordan Harband	Hemanth HM Jordan Harband	June 2020
	✓	await operations	Jack Works	Jack Works Jordan Harband	July 2020
	✓	Array.prototype.unique()	TechQuery	Jack Works	July 2020
✓	✓	Double-Ended Iterator and Destructuring	HE Shi-Jun	HE Shi-Jun	September 2020
	✓	Standardized Debug	Gus Caplan	Gus Caplan	November 2020 _
	✓	Modulus and Additional Integer Math	Peter Hoddie	Peter Hoddie	September 2020
✓		Extensions	HE Shi-Jun	HE Shi-Jun	November 2020
✓		Grouped Accessors and Auto-Accessors	Ron Buckton	Ron Buckton	November 2020
✓		async do expressions	Kevin Gibbons	Kevin Gibbons	January 2021
	✓	Class Brand Checks	HE Shi-Jun	HE Shi-Jun	January 2021
	✓	Limited ArrayBuffer	Jack Works	Jack Works	April 2021
✓	✓	BigInt Math	J.S. Choi	J.S. Choi	August 2021
	✓	Get Intrinsic	Jordan Harband	Jordan Harband	August 2021
✓	✓	Structs: Fixed Layout Objects and Some Synchronization Primitives	Shu-yu Guo	Shu-yu Guo	August 2021
	✓	String.cooked	Darien Maillet Valentine	Jamie Kyle Hemanth HM	October 2021
✓		Call-this operator	J.S. Choi	J.S. Choi	October 2021
✓	✓	RegExp Extended Mode and Comments	Ron Buckton	Ron Buckton	October 2021
✓	✓	RegExp \R Escape	Ron Buckton	Ron Buckton	December 2021
	✓	Reversible string split	Luca Casonato	Luca Casonato	January 2022
	✓	Function once	J. S. Choi	J. S. Choi	March 2022
✓		Type Annotations	Gil Tayar Daniel Rosenwasser Romulo Cintra Rob Palmer	Daniel Rosenwasser Romulo Cintra Rob Palmer	March 2022
	✓	Faster Promise adoption	Justin Ridgewell	Justin Ridgewell	June 2022
✓	✓	RegExp Atomic Operators	Ron Buckton	Ron Buckton	June 2022
	✓	Policy Maps and Sets	J.S. Choi	J.S. Choi Hemanth HM	July 2022
✓	✓	Function Memoization	J.S. Choi	J.S. Choi Hemanth HM	July 2022
✓		Object pick/omit	Hemanth HM Aleen	Hemanth HM	July 2022
✓	✓	Extractors	Ron Buckton	Ron Buckton	September 2022
	✓	Mass Proxy Revocation	Alex Vincent	Mark S. Miller, Jack Works	November 2022
✓	✓	Prototype pollution mitigation	Santiago Díaz Jun Kokatsu	Shu-yu Guo	January 2023
✓	✓	Await Dictionary	Alexander J. Vincent	Ashley Claymore Jordan Harband Chris de Almeida	March 2023
✓	✓	Class Method Parameter Decorators	Ron Buckton	Ron Buckton	March 2023
✓	✓	Optional chaining in assignment LHS	Nicolò Ribaudo	Nicolò Ribaudo	July 2023
	✓	DataView get/set Uint8Clamped methods	Jordan Harband	Jordan Harband	July 2023
	✓	Iterator Sequencing	Michael Ficarra	Michael Ficarra	September 2023
	✓	Stable Formatting	Eemeli Aro	Eemeli Aro	September 2023
✓		Negated in and instanceof operators	Pablo Gorostiaga Belio	Pablo Gorostiaga Belio	September 2023
	✓	Locale Extensions	Ben Allen	Ben Allen	September 2023
✓	✓	Module sync assert	Jack Works	Jack Works	November 2023
	✓	Iterator unique	Michael Ficarra	Michael Ficarra	February 2024
	✓	Micro and mini waits	Shu-yu Guo	Shu-yu Guo	February 2024
	✓	iterator chunking	Michael Ficarra	Michael Ficarra	February 2024
✓		Improved Escapes for Template Literals	HE Shi-Jun	HE Shi-Jun	February 2024
✓	✓	ESM Phase Imports	Luca Casonato Guy Bedford	Luca Casonato Guy Bedford	February 2024
✓	✓	Function and Object Literal Decorators	Ron Buckton	Ron Buckton	February 2024
✓	✓	"Discard" (void) Bindings	Ron Buckton	Ron Buckton	February 2024
	✓	Error.isError	Jordan Harband	Jordan Harband	April 2024
43/94	80/94

See also the active proposals, stage 0 proposals, finished proposals, and inactive proposals documents.

Stage 0 Proposals

Stage 0 proposals are either

• planned to be presented to the committee by a TC39 champion, or
• have been presented to the committee and not rejected definitively, but have not yet achieved any of the criteria to get into stage 1.

Syntactic	Semantic	Proposal	Author	Champion	Last Presented
✓	✓	Additional metaproperties	Allen Wirfs-Brock	Allen Wirfs-Brock
	✓	Defensible Classes	Mark Miller Doug Crockford	Mark Miller Doug Crockford
✓		Function bind syntax	Kevin Smith	Brian Terlson Matthew Podwysocki	March 2015
✓	✓	Function expression decorators	Igor Minar	Igor Minar
✓	✓	Method parameter decorators	Igor Minar	Igor Minar
✓	✓	Nested import declarations	Ben Newman	Ben Newman	July 2016
✓		Orthogonal Classes	Mark Miller Allen Wirfs-Brock	Mark Miller Allen Wirfs-Brock	March 2017
	✓	Reflect.{isCallable,isConstructor}	Caitlin Potter	Caitlin Potter
✓	✓	Relationships	Mark Miller Waldemar Horwat	Mark Miller Waldemar Horwat
	✓	Structured Clone	Dmitry Lomov	Dmitry Lomov	Jan 2014
	✓	WHATWG URL	James M Snell	James M Snell
✓		Object Shorthand Improvements	Ron Buckton	Ron Buckton	Sep 2017
✓	✓	as destructuring patterns	Kat Marchán	Kat Marchán
	✓	String trim characters	Wenlu Wang	Wenlu Wang
✓	✓	Catch Guard	Willian Martins	Willian Martins
10/15	12/15

See also the active proposals, stage 1 proposals, finished proposals, and inactive proposals documents.

Inactive Proposals

Inactive proposals are proposals that at one point were presented to the committee but were subsequently abandoned, withdrawn, or rejected.

Syntactic	Semantic	Proposal	Champion	Rationale
✓	✓	Callable class constructors	Yehuda Katz Allen Wirfs-Brock	Withdrawn: can be solved with decorators
	✓	{Set,Map}.prototype.toJSON	David Bruant Jordan Harband	Rejected: better solved by a custom replacer function.
	✓	Typed Objects	Till Schneidereit (previously Dmitry Lomov, Niko Matsakis)	Postponed: waiting for WebAssembly requirements to become clearer
	✓	Object enumerables	Leo Balter John-David Dalton	Rejected
	✓	Cancelable Promises	Domenic Denicola	Withdrawn
✓		Proposed Grammar change to ES Modules	Bradley Farias	Rejected: No consensus on this specific solution.
✓	✓	Dynamic Module Reform	Caridy Patiño	Withdrawn: we decided to preserve the current semantics
	✓	SIMD.JS - SIMD APIs	Peter Jensen Yehuda Katz	Stage 1: Start with SIMD in WASM; implementations not pursuing SIMD.js for now.
✓	✓	Updates to Tail Calls to include an explicit syntactic opt-in	Brian Terlson Eric Faust	Inactive
	✓	Object.shallowEqual	Sebastian Markbage	Withdrawn
✓	✓	%constructor%.construct	James M Snell	Withdrawn
	✓	Builtins.typeOf() and Builtins.is()	James M Snell	Withdrawn: can be solved in other ways
✓		Tagged Collection Literals	Kat Marchán	Withdrawn: pursuing when new syntax and other alternatives
	✓	Date.parse fallback semantics	Morgan Phillips	Inactive; likely replaced by uniform parsing of quasi-standard Date.parse input
✓	✓	Distinguishing literal strings	Mike West Adam Klein	Withdrawn: Trusted Types no longer a dependent
	✓	Annex B — HTML Attribute Event Handlers	Allen Wirfs-Brock	Withdrawn per PR comment
	✓	Normative ICU Reference	Domenic Denicola	Withdrawn; champion is no longer participating in TC39
	✓	Zones	Domenic Denicola Miško Hevery	Withdrawn; champion is no longer participating in TC39
✓	✓	Blöcks	Domenic Denicola	Withdrawn; champion is no longer participating in TC39
✓	✓	RegExp Atomic Groups & Possessive Quantifiers	Justin Ridgewell	Never presented; engines are not interested in the feature, mainly because it doesn't solve backtracking for most users
	✓	RefCollection	Robin Ricard	Withdrawn; replaced with Symbols as WeakMap keys; also there were OCAP/membrane concerns around providing a globally available pre-instantiated RefCollection
✓	✓	Generic Comparison	Hemanth HM Jordan Harband	Withdrawn: replaced with Array Equality
✓		from ... import	Bradley Farias	Never presented; preliminary feedback about syntax cost not being worth the weight
	✓	TypedArray stride parameter	Shu-yu Guo	Withdrawn: concern about performance implications, and the proposal is not expressive enough
✓		Unused Function Parameters	Gus Caplan	Rejected: the need to solve the problem does not outweigh the hazards
	✓	Improving iteration on Objects	Jonathan Keslin	Withdrawn: concern about need for such an API
	✓	String.prototype.at	Mathias Bynens Rick Waldron	Obsoleted by renamed String.prototype.item proposal
	✓	ArrayBuffer.prototype.transfer	Domenic Denicola Shu-yu Guo	Withdrawn: superseded by Resizable Buffers
✓		deprecated	James M Snell	Never presented
	✓	Function helpers	J. S. Choi	Presented and rejected before Stage 1 on 2021-10; split up into multiple subsequent proposals
✓		"use module"	Dave Herman	Inactive; champion does not wish to pursue
	✓	Function.pipe and flow	J.S. Choi	Withdrawn: rejected for stage 1
	✓	Symbol.thenable	Gus Caplan Jordan Harband Myles Borins	Withdrawn; changing thenability on Module Namespace objects is not web compatible, and allowing non-Promise use of "then" is not worth slowing down all Promise operations
	✓	WeakRefs cleanupSome	Yulia Startsev Daniel Ehrenberg	Withdrawn; subsumed by WebAssembly JS Promise Integration, which avoids the long task issue
✓	✓	Operator overloading	Daniel Ehrenberg	Withdrawn
✓		Extensible numeric literals	Daniel Ehrenberg	Withdrawn
	✓	JSON.tryParse	Jack Works	Rejected; some deemed this too specific a solution for a generalized language-wide problem
	✓	Math Extensions	Rick Waldron	Withdrawn: no interested champions in February 2024
✓		Generator arrow functions	Sergey Rubanov Brendan Eich	Withdrawn: no interested champions in February 2024
	✓	Math.signbit: IEEE-754 sign bit	JF Bastien	Withdrawn: no interested champions in February 2024
	✓	Getting last element of Array	Keith Cirkel	Withdrawn; the Array#at proposal supersedes this work.
✓	✓	Sequence properties in Unicode property escapes	Mathias Bynens	Withdrawn; subsumed by RegExp v flag with set notation + properties of strings proposal
18/42	34/42

See also the active proposals, stage 1 proposals, stage 0 proposals, and finished proposals documents.