<!-- style comments not recognized when parsing JSX

[aaronshaf]

Evidently <!-- ... single-line comments are valid in JavaScript. eslint doesn't seem to recognize this.

Source: https://twitter.com/bterlson/status/768211703314067457 and http://www.ecma-international.org/ecma-262/7.0/index.html#prod-annexB-SingleLineHTMLOpenComment

[ljharb]

They're in annex B, which means non-web browsers don't have to implement parsing for it.

That said, it does seem useful for eslint to be able to parse them, if only so a rule can be created that forbids them :-)

[mysticatea]

Thank you for this issue.

Acorn, the base of our parser, does not support HTML style comments, so it needs to implement in Acorn.

[aaronshaf]

Thanks. I created the issue: acornjs/acorn#454

[mysticatea]

I'm sorry.
I re-confirmed that <!-- seems to be handled as single line comment correctly.

[platinumazure]

@mysticatea Do we need to do anything in espree, then, in order to get the comment to show up? Or maybe the problem is only in attaching the comments to code nodes? What's our next step here?

[mysticatea]

Espree seems to handle the HTML comments as single line comments.
So, I think we don't need to do something for this.

(Probably I saw a ghost around this issue...)

[mysticatea]

I got a fact that HTML comments trigger a syntax error if it's using JSX option.
I reopen this issue.

$ echo "<!--" | eslint --stdin --no-eslintrc

no errors

$ echo "<!--" | eslint --stdin --no-eslintrc --parser-options "ecmaFeatures:{jsx:true}"

<text>
  1:2  error  Parsing error: Unexpected token !

✖ 1 problem (1 error, 0 warnings)

[mysticatea]

I opened the issue: acornjs/acorn-jsx#41

[mysticatea]

acorn-jsx's issue has been fixed now.
This issue will be fixed after espree upgrades acorn-jsx to 4.0.1.

[nzakas]

@mysticatea has this issue been fixed in Espree now? Can we close this issue?

[mysticatea]

Yes, it has been fixed. Thank you for pinging!