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tc39

38 indexed repositories · View on GitHub

proposals
Tracking ECMAScript Proposals

19185 stars
ecma262
Status, process, and documents for ECMA-262

HTML · 15690 stars
proposal-temporal
Provides standard objects and functions for working with dates and times.

HTML · 3709 stars
proposal-decorators
Decorators for ES6 classes

2977 stars
test262
Official ECMAScript Conformance Test Suite

JavaScript · 2821 stars
agendas
TC39 meeting agendas

JavaScript · 1173 stars
notes
TC39 meeting notes

JavaScript · 715 stars
proposal-decimal
Built-in exact decimal numbers for JavaScript

HTML · 638 stars
ecma402
Status, process, and documents for ECMA 402

HTML · 610 stars
tc39.github.io
Get involved in specifying JavaScript

HTML · 336 stars
proposal-defer-import-eval
A proposal for introducing a way to defer evaluate of a module

HTML · 320 stars
proposal-composites

TypeScript · 293 stars
ecmarkup
An HTML superset/Markdown subset source format for ECMAScript and related specifications

TypeScript · 245 stars
proposal-Declarations-in-Conditionals

JavaScript · 194 stars
ecma426
Source map specification, RFCs and new proposals.

JavaScript · 186 stars
proposal-await-dictionary
A proposal to add Promise.allKeyed to ECMAScript

JavaScript · 163 stars
eshost
A uniform wrapper around a multitude of ECMAScript hosts. CLI: https://github.com/bterlson/eshost-cli

JavaScript · 147 stars
proposal-iterator-chunking
a proposal to add a method to iterators for producing an iterator of its subsequences

JavaScript · 104 stars
proposal-intl-locale-info
An API to expose information of locale, such as week data ( first day of a week, weekend start, weekend end), hour cycle, measurement sys...

HTML · 60 stars
proposal-deferred-reexports

60 stars
18 more repositories live on View on GitHub

Beginner friendly Everything

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Concerns with the filtered namespace Environment Record design Open

Difficulty 5/5 Over a week Newbie friendliness 25/100

tc39/proposal-deferred-reexports#58 · Opened Sep 19, 2026
Normative Suggestion: Treat `export defer * as ns` as a deferred namespace Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

tc39/proposal-deferred-reexports#57 · 1 comment · Opened Sep 19, 2026
Dynamic `exports` validation rejects with `ReferenceError`, while static case throws `SyntaxError` Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

tc39/proposal-deferred-reexports#56 · Opened Sep 19, 2026
`export * as ns` does not validate deferred reexports, unlike `import * as ns` Open

Difficulty 5/5 Over a week Newbie friendliness 45/100

tc39/proposal-deferred-reexports#55 · Opened Sep 19, 2026
Dynamic filtered namespace imports not executing optional dependencies Open

Difficulty 3/5 1-2 days Newbie friendliness 68/100

tc39/proposal-deferred-reexports#54 · Opened Sep 19, 2026
ECMA-262 Regression: TypeError for valid hoisted function execution Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

tc39/proposal-deferred-reexports#53 · Opened Sep 19, 2026
ECMA-262 Regression: ~disallow-ambiguous~ check in InitializeEnvironment throws for ambiguous star names that link today Open

Difficulty 4/5 3-5 days Newbie friendliness 48/100

tc39/proposal-deferred-reexports#52 · Opened Sep 19, 2026
Assertion Failure: Invalid assertion during deferred namespace execution of existing evaluation graph Open

Difficulty 4/5 3-5 days Newbie friendliness 45/100

tc39/proposal-deferred-reexports#51 · Opened Sep 19, 2026
Non-termination in valid BuildEvaluationList for namespace cases Open

Difficulty 4/5 3-5 days Newbie friendliness 52/100

tc39/proposal-deferred-reexports#50 · Opened Sep 19, 2026
Assertion Failure: Invalid [[TopLevelCapability]] assertion for Evaluate() when encountering already-evaluated dependencies Open

Difficulty 3/5 1-2 days Newbie friendliness 70/100

tc39/proposal-deferred-reexports#49 · Opened Sep 19, 2026
Invalid star reexport ambiguity check with import defer Open

Difficulty 2/5 1-3 hours Newbie friendliness 76/100

tc39/proposal-deferred-reexports#48 · Opened Sep 19, 2026
Polyfill: time zone transitions before 1847 are not found (Asia/Manila and four Pacific zones on 1844-12-31) Open

Difficulty 1/5 Under an hour Newbie friendliness 92/100

tc39/proposal-temporal#3330 · 1 comment · Opened Sep 19, 2026
Input unit type checking Open

agenda

Difficulty 5/5 Over a week Newbie friendliness 25/100

tc39/proposal-intl-unit-protocol#8 · 1 comment · Opened Sep 19, 2026
Should we check for the protocol even if the formatter is not a unit/currency formatter? Open

agenda

Difficulty 5/5 Over a week Newbie friendliness 30/100

tc39/proposal-intl-unit-protocol#7 · Opened Sep 19, 2026
ParseModule must set [[DeferredNamespace]] in its constructor Open

Difficulty 3/5 1-2 days Newbie friendliness 50/100

tc39/proposal-defer-import-eval#88 · Opened Sep 19, 2026
Minification flattens Prince's @prince-overlay inside @page, breaking printable output Open

Difficulty 3/5 1-2 days Newbie friendliness 68/100

tc39/ecmarkup#729 · 2 comments · Opened Sep 18, 2026
Polyfill: calendarToIsoDate overshoot assertion from #3292 is reachable in coptic/ethiopic/ethioaa month 13 Open

Difficulty 2/5 1-3 hours Newbie friendliness 86/100

tc39/proposal-temporal#3329 · Opened Sep 18, 2026
Polyfill: GetNamedTimeZoneNextTransition misses a transition in the last search window before the max Instant Open

Difficulty 2/5 1-3 hours Newbie friendliness 84/100

tc39/proposal-temporal#3328 · 1 comment · Opened Sep 18, 2026
Polyfill: non-ISO until() by months gives wrong results since #3245, and throws near the range limits Open

Difficulty 3/5 1-2 days Newbie friendliness 76/100

tc39/proposal-temporal#3327 · 1 comment · 1 reaction · Opened Sep 18, 2026
non-undefined non-boolean options should throw Open

Difficulty 3/5 1-2 days Newbie friendliness 55/100

tc39/proposal-json-parseimmutable#20 · 1 comment · Opened Sep 17, 2026
Web compat for changing semantics of nested same-name private fields Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

tc39/proposal-private-declarations#23 · 2 comments · 3 reactions · Opened Sep 17, 2026
Use an array instead of an object Open

agenda

Difficulty 2/5 1-3 hours Newbie friendliness 65/100

tc39/proposal-intl-sequence-units#16 · Opened Sep 17, 2026
Stage 2.7 editors review for "deferred re-exports" Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

tc39/proposal-deferred-reexports#45 · Opened Sep 16, 2026
Stage 2.7 reviews for "Include default in `export * from`" Open

Difficulty 4/5 3-5 days Newbie friendliness 25/100

tc39/proposal-export-star-default#4 · 6 comments · Opened Sep 16, 2026
Consider adding negative Test For Invalid BigInt literals Open

Difficulty 2/5 1-3 hours Newbie friendliness 78/100

tc39/test262#5133 · 1 comment · Opened Sep 10, 2026
Spec review comments Open

Difficulty 3/5 1-2 days Newbie friendliness 48/100

tc39/proposal-json-parseimmutable#16 · 3 comments · Opened Sep 8, 2026
Coverage candidates discovered while implementing Generator semantics in an ECMAScript companion language Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

tc39/test262#5131 · Opened Sep 7, 2026
Uint8Array.prototype.toHex tests do not test for padding Open

Difficulty 1/5 Under an hour Newbie friendliness 90/100

tc39/test262#5130 · Opened Sep 7, 2026
Stage 2.7 review for JSON.parse Options Open

Difficulty 5/5 Over a week Newbie friendliness 25/100

tc39/proposal-json-parseimmutable#14 · 10 comments · Opened Sep 3, 2026
Can we drop test file contents from Engine tests GitHub artifacts? Open

Difficulty 3/5 1-2 days Newbie friendliness 58/100

tc39/test262#5127 · Opened Sep 2, 2026
Data on prevalence of hardware without FMA Open

Difficulty 4/5 3-5 days Newbie friendliness 25/100

tc39/proposal-fma#5 · 1 reaction · Opened Sep 2, 2026
Should a default locale be allowed to have a Unicode locale extension sequence? Open

c: locale s: discuss

Difficulty 5/5 Over a week Newbie friendliness 35/100

tc39/ecma402#1098 · Opened Sep 2, 2026
Should we have a `region` option instead of `locale`? Open

Difficulty 5/5 Over a week Newbie friendliness 25/100

tc39/proposal-amount#158 · Opened Sep 2, 2026
Should self-resolution be special cased. Open

Difficulty 5/5 Over a week Newbie friendliness 45/100

tc39/proposal-thenable-curtailment#20 · 3 comments · Opened Aug 31, 2026
Compound `-per-` units should be supported Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

tc39/proposal-amount#157 · 3 comments · Opened Aug 31, 2026
Testing plan for Thenable-Curtailment (Safe Promise Resolve) Open

Difficulty 5/5 Over a week Newbie friendliness 38/100

tc39/test262#5122 · 1 comment · Opened Aug 31, 2026
convertTo into sequence units should not use Euclidean division Open

Difficulty 3/5 1-2 days Newbie friendliness 65/100

tc39/proposal-amount#156 · Opened Aug 31, 2026
`GetNumberFormatPattern`'s unit reconciliation unreachable from `Amount.p.toLocaleString` Open

Difficulty 3/5 1-2 days Newbie friendliness 70/100

tc39/proposal-amount#154 · 1 comment · Opened Aug 31, 2026
JSON.stringify replacer options bag Open

Difficulty 5/5 Over a week Newbie friendliness 25/100

tc39/proposal-json-parseimmutable#12 · 1 comment · Opened Aug 31, 2026
We need an equality function Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

tc39/proposal-amount#153 · 4 comments · Opened Aug 27, 2026
create AI policy Open

group process

Difficulty 5/5 Over a week Newbie friendliness 30/100

tc39/test262#5115 · 1 comment · 2 reactions · Opened Aug 24, 2026
ECMA-402 should define overriding of %TypedArray%.prototype.toLocaleString Open

Difficulty 3/5 1-2 days Newbie friendliness 68/100

tc39/ecma402#1094 · 2 comments · Opened Aug 23, 2026
Expose whether an `ArrayBuffer` is detachable Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

tc39/proposal-immutable-arraybuffer#63 · Opened Aug 21, 2026
Should we prefer SDOs that handle multiple productions by branching on parse node presence? Open

establishes editorial conventions

Difficulty 2/5 1-3 hours Newbie friendliness 72/100

tc39/ecma262#3954 · 3 comments · Opened Aug 20, 2026
annexB block-decl-func-skip-arguments contradicts staging/sm block-scoped-functions-annex-b-arguments Open

Difficulty 2/5 1-3 hours Newbie friendliness 86/100

tc39/test262#5113 · Opened Aug 20, 2026
GetPreferredUnits asserts constraints on its region argument instead of expressing them in the parameter type Open

Difficulty 3/5 1-2 days Newbie friendliness 68/100

tc39/proposal-amount#151 · Opened Aug 19, 2026
Expose an `isWeakKey` or similar function Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

tc39/proposal-composites#39 · 6 comments · Opened Aug 17, 2026
Significant digit formatting is problematic with sequence units Open

agenda

Difficulty 5/5 Over a week Newbie friendliness 35/100

tc39/proposal-intl-sequence-units#14 · Opened Aug 16, 2026
Underspecified sorting step for mappings Open

Difficulty 3/5 1-2 days Newbie friendliness 48/100

tc39/ecma426#273 · 1 comment · Opened Aug 15, 2026
Consider adding 's' and 'n' to serialized form for String and BigInt Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

tc39/proposal-amount#147 · 4 comments · Opened Aug 13, 2026

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