Microsoft/TypeScript

Comment like jsx text emitted twice when preserve enabled

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#61,860 opened on Jun 13, 2025

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BugDomain: JSX/TSXHelp Wanted

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Description

🔎 Search Terms

comment like jsx text, preserve jsx

🕗 Version & Regression Information

  • This is the behavior in every version I tried, and I reviewed the FAQ for entries about _________

⏯ Playground Link

https://www.typescriptlang.org/play/?jsx=1#code/GYVwdgxgLglg9mABAQQA6oBQEpEG8C+AUMRAgM5SIBWZAHogLyIA8aqAfAPQBUiYcibp1w9EARkGdxAJgDMiUdMn5R-Sc05t2AbkJA

💻 Code

function App() {}
const jsx = <App>/* no */{/* 1 */ 123 /* 2 */}/* no */</App>;

🙁 Actual behavior

These duplicate sections will be rendered in the JSX text output:

"use strict";
function App() { }
const jsx = <App> /* no *//* no */{/* 1 */123 /* 2 */} /* no *//* no */</App>
//                ~~~~~~~                              ~~~~~~~

🙂 Expected behavior

"use strict";
function App() { }
- const jsx = <App> /* no *//* no */{/* 1 */123 /* 2 */} /* no *//* no */</App>
+ const jsx = <App> /* no */{/* 1 */123 /* 2 */} /* no */</App>

Additional information about the issue

No response

Contributor guide

Research direction
Inspect the JSX emitter in the TypeScript compiler, specifically the code that handles comment like text blocks in preserve mode (jsx mode 'preserve'). Look for duplicate emission when a comment like string is adjacent to JSX expressions or other JSX text.
Tech stack
typescript
Domain
backend
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Half day
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
TypeScriptGit
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
55