Changelog

tc39/ecma262 · Aug 3–9, 2026 · 18 commits

TC39 adds shared index helpers and tightens TypedArray rules

A quiet week with two notable spec cleanups: reusable index helpers across built-ins and a clearer TypedArray validation model.

Shared index conversion helpers spread across the spec

The biggest cross-cutting change this week introduces reusable ToAbsoluteIndex and ToClampedIndex abstract operations, then applies them to many string, array-like, and typed-array algorithms. This consolidates repeated negative-index and clamping logic in methods like at, includes, indexOf, slice, copyWithin, and related TypedArray operations, making the spec more consistent and easier to maintain.

TypedArray validation is factored into clearer shared steps

TypedArray-related text saw another meaningful refactor with a dedicated witness-record validation step. The new abstraction is meant to support ValidateTypedArray and related algorithms more cleanly, improving readability around bounds validation and memory-model-sensitive wording. Several smaller follow-up edits also aligned ValidateIntegerTypedArray and IsNoTearConfiguration with this structure.

Execution-context and generator resumption wording was clarified

The spec updated resumption language around suspended execution contexts from “Return” to “passing,” better matching the control flow being described. A few generator and async-generator algorithms were adjusted to model resumption explicitly, improving precision without changing behavior.

Editorial cleanup and terminology normalization

The week also included a batch of smaller editorial fixes: canonical RFC links were normalized, time-related notes were updated for modern ISO 8601 and RFC 9557 terminology, and an autolinked definition for “expanded year” was added. There were also minor cleanup passes around time constants, DoWait coercion, private-element wording, and spec assertions/typecheck fixes.

Other misc changes

  • Moved an editorial note for CRLF line-terminator text
  • Refactored TypedArraySpeciesCreate argument-count wording in subarray
  • Removed some unused unions and tightened a few wording details