Changelog

tc39/ecma262 · Apr 27 – May 3, 2026 · 3 commits

Spec gets stricter on types and comparison semantics

A small editorial week that tightens abstract operation signatures and clarifies core comparison and shared-memory wording.

More precise abstract operation signatures

The spec now narrows a broad set of abstract operation parameter and return types, replacing generic values with more specific kinds such as function objects, Objects, non-negative integers, finite numbers, and time values. This is mostly editorial, but it improves implementability and reduces ambiguity across the spec.

Comparison and shared-memory wording corrected

IsLessThan now more clearly states that it returns undefined when operands cannot be coerced to comparable values of the same numeric type, not just when one operand is NaN. The week also restored an earlier shared-memory event condition after an accidental wording regression, keeping the happens-before/overlap logic aligned with the intended semantics.

Other misc changes

  • Minor prose refinements around IsLessThan and memory-ordering text
  • No changes for the rest of the week