Stage 4 (Finished)

What is it? The proposal is ready to be included in the standard.

What’s required? The following things are needed before a proposal can reach this stage:

Test 262 acceptance tests (roughly, unit tests for the language feature, written in JavaScript).
Two spec-compliant shipping implementations that pass the tests.
Significant practical experience with the implementations.
The ECMAScript spec editor must sign off on the spec text.

What’s next? The proposal will be included in the ECMAScript specification as soon as possible. When the spec goes through its yearly ratification as a standard, the proposal is ratified as part of it.

These stage details are taken from Dr. Axel Rauschmayer's blog post. You can read more about the TC39 process in their official process document.

Optional Chaining
4984
import()
1812
Async functions
1571
Rest/Spread Properties
1475
Nullish coalescing Operator
1219
Top-level await
1014
Asynchronous Iteration
841
BigInt
557
WeakRefs
385
Shared memory and atomics
364
globalThis
336
Error Cause
334
.at()
326
Object.fromEntries
316
Numeric separators
315
Promise.allSettled
313
Logical Assignment Operators
295
Promise.prototype.finally
279
String.prototype.replaceAll
247
RegExp named capture groups
221
Array.prototype.{flat,flatMap}
215
Intl.RelativeTimeFormat
212
Promise.any
196
Array.prototype.includes
145
import.meta
135
RegExp Unicode Property Escapes
120
Accessible Object.prototype.hasOwnProperty
120
Trailing commas in function parameter lists and calls
118
Intl.Segmenter: Unicode Segmentation in JavaScript
112
JSON superset
102
Class Static Block
99
String.prototype.matchAll
96
RegExp Lookbehind Assertions
94
s (dotAll) flag for regular expressions
89
Object.values/Object.entries
88
Exponentiation operator
87
Optional catch binding
87
String padding
70
Well-formed JSON.stringify
65
RegExp Match Indices
57
for-in mechanics
45
Intl.NumberFormat Unified API Proposal
45
Intl.DisplayNames
41
String.prototype.{trimStart,trimEnd}
39
Lifting template literal restriction
36
Ergonomic brand checks for Private Fields
33
Intl.Locale
32
DateTimeFormat dateStyle & timeStyle
27
Intl.DateFormat.prototype.formatRange
27
Intl.PluralRules
26
Intl.ListFormat
26
Object.getOwnPropertyDescriptors
25
Function.prototype.toString revision
25
Intl.DateTimeFormat.prototype.formatToParts
16
Intl.NumberFormat.prototype.formatToParts
16
Symbol.prototype.description
13
Class Fields (Private instance methods and accessors, Class Public Instance Fields & Private Instance Fields, Static class fields and private static methods)