Microsoft/TypeScript

`ReadonlySet` lacks documentation for `has`, `forEach` and `size`

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#63481 opened on May 15, 2026

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Domain: lib.d.tsHelp WantedPossible Improvement

Description

⚙ Compilation target

ES2015+

⚙ Library

lib.es2015.collection.d.ts

Missing / Incorrect Definition

ReadonlySet<T> lacks documentation for forEach, has and size.

These should ideally be copied from regular Set<T> for consistency.

Sample Code

https://www.typescriptlang.org/play/?#code/MYewdgzgLgBA5gLhgZQKZQDzQE4EsxwB8MAvDGKgO4roAUA2gEQBMjAugJQDcAUKJLABmSAEqoAhgBNwAGwCeaTDnxFS8XjwD0mmAAkQAN1TYYh4zHFhJMCKlQwoAC3uTcgwcdRhg9gLTwYR3EIGGlgEMpHXBl7QRgZcWAAaxCnVABbHkEAOkEQbABRRMceOFz8ouASnKCIUuzarOyIXAAvVHqW9p4gA

Documentation Link

N/A

Contributor guide

Tech stack
typescript
Domain
documentation
Issue type
documentation
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
under 1 hour
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
TypeScript basicsknowledge of lib.es2015.collection.d.ts
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
90
Research direction
Look at the lib.es2015.collection.d.ts file in the TypeScript repository to find the ReadonlySet interface. Compare the JSDoc comments on ReadonlySet's methods (has, forEach, size) with those on the Set interface. The fix involves copying the documentation from Set's corresponding methods to ReadonlySet, ensuring consistency.