Microsoft/TypeScript

Markdown heading level bug in Narrowing documentation

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#63,531 opened on Jun 4, 2026

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Description

Acknowledgement

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Comment

URL: https://www.typescriptlang.org/docs/handbook/2/narrowing.html#truthiness-narrowing

Issue: In the "Narrowing" handbook page, the heading for "Truthiness narrowing" is written as an H1 (# Truthiness narrowing) instead of an H2 (## Truthiness narrowing).

Because of this markdown typo, all the subsequent parallel narrowing concepts (Equality narrowing, The in operator narrowing, instanceof narrowing, etc.) are incorrectly nested under "Truthiness narrowing" in the Table of Contents, which might confuse readers into thinking they are sub-concepts of Truthiness narrowing.

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.
1
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.
active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
None
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
95
Research direction
Correct the heading level from H1 to H2 for the 'Truthiness narrowing' section in the narrowing documentation file. Update the markdown heading accordingly.