HTML Attributes without quote is broken

[rhysd]

Marked version: 0.3.17

Markdown flavor: Markdown.pl|CommonMark|GitHub Flavored Markdown

Expectation

Marked can handle HTML attributes without quote like <a href=https://example.com></a> in markdown doc. It should be converted into <p><a href="https://example.com"></a></p>, the same as <a href="https://example.com"></a>.

Result

Converted into broken HTML <p>&lt;a href=<a href="https://example.com&gt;">https://example.com&gt;</a></a></p>

What was attempted

1. npm install marked
2. Put following code to foo.js
3. Run node foo.js

const marked = require('marked');
console.log(marked('<a href=https://example.com></a>'));

Call stack & console log

<p>&lt;a href=<a href="https://example.com&gt;">https://example.com&gt;</a></a></p>

though I expected

<p><a href="https://example.com"></a></p>

[joshbruce]

Not sure I agree with this desired behavior actually; see HTML spec: https://www.w3.org/TR/html52/dom.html#elements

There is no example in which the HTML attributes exist without quotation. Therefore, this may be one of those moments of should we do this. Do we really want to begin creating the habit of not encasing attribute values in quotes? What value is there to the developer?

<[element name] [attribute]="[value(s)]">

<[element name] [attribute]="[value(s)]">[content]</[element name]>

<!-- not, strictly speaking, valid HTML -->
<[element name] [attribute]=[value(s)]>

<[element name] [attribute]=[value(s)]>[content]</[element name]>

Allowing for non quoted attributes also could make it harder on Marked because we have to cover both use cases - quoted and non-quoted. What happens with the following case:

<a class=something something-else one-more-class>Hello, World!</a>

How do we determine what to encapsulate in quotes?

[joshbruce]

Ps. Also not sure this is referenced in the CommonMark and GFM specs. If it is, please point us to the proper example.

[UziTech]

From CommonMark spec:

An attribute value consists of an unquoted attribute value, a single-quoted attribute value, or a double-quoted attribute value.

https://spec.commonmark.org/0.28/#attribute-value

An unquoted attribute value would only be up to whitespace so your example would be encapsulated as follows:

<a class="something" something-else one-more-class>Hello, World!</a>

[joshbruce]

@UziTech: Thanks for the spec reference. I don't see any examples that actually use unquoted attributes. Having said that, I ran tests against a couple of the examples from the spec and none of them pass.