ある機能がどのECMAバージョンで入ったのかの一覧表。ある程度グルーピングをしてある。

2025年現在のproposalsのfinished-proposals.mdを参照している。

(なお、全部確認はしたはずだが、間違ってる可能性もある。抜け等あったらコメントお願いします🙏)

Array

• ES2016: Array.prototype.includes
• ES2019: Array.prototype.{flat,flatMap}
• ES2020: Optional Chaining ?.[]
• ES2022: Array.prototype.at()
• ES2023: Array.prototype.{findLast,findLastIndex}
• ES2023: Change Array by Copy
  • Array.prototype.toReversed
  • Array.prototype.toSorted
  • Array.prototype.toSpliced
  • Array.prototype.with
• ES2024: Array Grouping
  • Object.groupBy, Map.groupBy

Atomic

• ES2017: Shared memory and atomics
• ES2024: Atomics.waitAsync

Class

• ES2022: Class Fields (Private instance methods and accessors, Class Public Instance Fields & Private Instance Fields, Static class fields and private static methods)
• ES2022: Class Static Block
• ES2022: Ergonomic brand checks for Private Fields

Function

• ES2017: Async functions
• ES2017: Trailing commas in function parameter lists and calls
• ES2019: Function.prototype.toString revision
• ES2020: Optional Chaining ?.()

Module

• ES2019: JSON superset
• ES2020: import()
• ES2020: import.meta
• ES2025: Import Attributes
• ES2025: JSON Modules

Object

• ES2017: Object.getOwnPropertyDescriptors
• ES2017: Object.values/Object.entries
• ES2018: Rest/Spread Properties
• ES2019: Object.fromEntries
• ES2020: Optional Chaining ?.
• ES2022: Object.hasOwn (Accessible Object.prototype.hasOwnProperty)
• ES2024: Object.groupBy (Array Grouping)

Operator

• ES2016: ** (Exponentiation operator)
• ES2020: ?? (Nullish coalescing Operator)
• ES2021: ||=, &&=, ??= (Logical Assignment Operators)

Promise

• ES2018: Promise.prototype.finally
• ES2020: Promise.allSettled
• ES2021: Promise.any
• ES2024: Promise.withResolvers
• ES2025: Promise.try

RegExp

• ES2018: RegExp Lookbehind Assertions
• ES2018: RegExp Unicode Property Escapes
• ES2018: RegExp named capture groups
• ES2018: s (dotAll) flag for regular expressions
• ES2022: RegExp Match Indices
• ES2024: RegExp v flag with set notation + properties of strings
• ES2025: Duplicate named capture groups
• ES2025: RegExp Modifiers
• ES2025: RegExp.escape

String

• ES2017: String.prototype.{padStart,padEnd}
• ES2019: String.prototype.{trimStart,trimEnd}
• ES2020: String.prototype.matchAll
• ES2021: String.prototype.replaceAll
• ES2022: String.prototype.at()
• ES2024: Well-Formed Unicode Strings

TypedArray

• ES2022: TypedArray.prototype.at()
• ES2023: Change Array by Copy
  • TypedArray.prototype.toReversed
  • TypedArray.prototype.toSorted
  • TypedArray.prototype.with

Other

• ES2018: Asynchronous Iteration
• ES2018: Lifting template literal restriction
• ES2019: Well-formed JSON.stringify
• ES2019: Optional catch binding
• ES2019: Symbol.prototype.description
• ES2020: for-in mechanics
• ES2020: BigInt
• ES2020: globalThis
• ES2021: Numeric separators
• ES2021: WeakRefs
• ES2022: Error Cause
• ES2022: Top-level await
• ES2023: Hashbang Grammar
• ES2023: Symbols as WeakMap keys
• ES2024: ArrayBuffer transfer
• ES2024: Resizable and growable ArrayBuffers
• ES2025: Float16 on TypedArrays, DataView, Math.f16round
• ES2025: New Set methods
  • Set.prototype.intersection
  • Set.prototype.union
  • Set.prototype.difference
  • Set.prototype.symmetricDifference
  • Set.prototype.isSubsetOf
  • Set.prototype.isSupersetOf
  • Set.prototype.isDisjointFrom
• ES2025: Sync Iterator helpers