Don't remove stars from alt attribute of an image

[talatkuyuk]

Initial checklist

• I read the support docs
• I read the contributing guide
• I agree to follow the code of conduct
• I searched issues and discussions and couldn’t find anything (or linked relevant results below)

Affected package

mdast-util-from-markdown

Steps to reproduce

const input = '![*text*](image.png "*title*")';

console.dir(fromMarkdown(input), {depth: null});

Actual behavior

It removes the stars from "alt", keeps stars in "title"

{
  "alt": "text",
  "title": "*title*",
  "type": "image",
  "url": "image.png",
},

Expected behavior

It should keep stars in "alt" as well.

{
  "alt": "*text*",
  "title": "*title*",
  "type": "image",
  "url": "image.png",
},

But, I see that commonmark specs also removes stars from "alt". I couldn't get the rationale of removing stars from "alt", whileas doesn't remove stars from "title". It would be better to keep stars in "alt", so I would use it as a directive for images for transformation in a plugin.

I know, you will close the issue pointing commonmark specs. I just wanted to know the rationale in commonmark specs?

(why I opened this issue is because the next question will be why curly braces are also removed from "alt" attribute of an image when remark-mdx parse it; at least I would expect curly braces are kept in "alt" when remark-mdx parse it since commonmark specs also keeps the curly braces in alt attribute. This issue is critic for me because of this discussion)

Runtime

node@latest

Package manager

npm@latest

Operating system

macos@latest

Build and bundle tools

No response

[ChristianMurphy]

It comes from this line in the spec

Though this spec is concerned with parsing, not rendering, it is recommended that in rendering to HTML, only the plain string content of the image description be used.

https://spec.commonmark.org/0.31.2/#example-575

And is because alt is intended for screen readers and extra symbols are for sighted users and are handled inconsistency (at best) by screen readers, traditionally asterisk are ignored by screen readers and should not be included in text or alt text intended to be consumed by a reader.
https://www.deque.com/blog/dont-screen-readers-read-whats-screen-part-1-punctuation-typographic-symbols/