Microsoft/TypeScript
View on GitHubJSDoc comments emitted a second time even after commenrs on type are emitted
Open
#62453 opened on Sep 15, 2025
BugDomain: Comment EmitHelp Wanted
Description
🔎 Search Terms
JSDoc, emit, comments
🕗 Version & Regression Information
v5.9.2
- I was unable to test this on prior versions because I was not using TS.
⏯ Playground Link
No response
💻 Code
/**
* The template passed to generate messages
*
* @callback Template
* @param {...*} args - Arguments to the template
* @returns {any} The generated message
*/
/**
* The arguments sent with notify become the input parameters for the template.
*
* @typedef {Parameters<Template>} TemplateParams
*/
/**
* The return value from the template is yielded as the message generated from
* the subscription. The following types help define this relationship.
*
* @typedef {ReturnType<Template>} Message
*/
🙁 Actual behavior
Typescript, when emitting from JSDoc, seems to want to emit the same comments for a type declaration twice:
- once for the export (good) and
- once just copying over the JSDoc comment (bad).
/**
* The template passed to generate messages
*/
export type Template = (...args: any[]) => any;
/**
* The arguments sent with notify become the input parameters for the template.
*/
export type TemplateParams = Parameters<Template>;
/**
* The return value from the template is yielded as the message generated from
* the subscription. The following types help define this relationship.
*/
export type Message = ReturnType<Template>;
/**
* The template passed to generate messages
*
* @callback Template
* @param {...*} args Arguments to the template
* @returns {any} The generated message
*/
/**
* The arguments sent with notify become the input parameters for the template.
*
* @typedef {Parameters<Template>} TemplateParams
*/
/**
* The return value from the template is yielded as the message generated from
* the subscription. The following types help define this relationship.
*
* @typedef {ReturnType<Template>} Message
*/
🙂 Expected behavior
It should emit the comment just once:
/**
* The template passed to generate messages
*/
export type Template = (...args: any[]) => any;
/**
* The arguments sent with notify become the input parameters for the template.
*/
export type TemplateParams = Parameters<Template>;
/**
* The return value from the template is yielded as the message generated from
* the subscription. The following types help define this relationship.
*/
export type Message = ReturnType<Template>;
or even better (See #61664)
/**
* The template passed to generate messages
*
* @param Arguments to the template
* @returns The generated message
*/
export type Template = (...args: any[]) => any;
/**
* The arguments sent with notify become the input parameters for the template.
*/
export type TemplateParams = Parameters<Template>;
/**
* The return value from the template is yielded as the message generated from
* the subscription. The following types help define this relationship.
*/
export type Message = ReturnType<Template>;
Additional information about the issue
No response