"Expected valid tag name" when using special characters like <

Hello @pngwn, thank you for this great project!

I am having an issue when using the < character inside a Markdown file. Even when replacing it with <. It seems the < gets replaced by < again resulting in the same error from the svelte compiler (“Expected valid tag name”). I even tried to escape the character with \ without success.

Is there any way to escape special characters so the svelte compiler does not throw an error?

My current “solution” is to wrap < inside an inline code block but I do not want to show that part as code. This is the Markdown file I am talking about: https://github.com/nymea/nymea-plugins/blob/rework-readmes/awattar/README.md This is the version with the “fixed” inline code blocks. When removing those, the error gets thrown.

I am not sure if this is a bug or if I miss something here. Just found this code section in MDSveX:

// in code nodes replace the character witrh the html entities
// maybe I'll need more of these

const entites = [
	[/</g, '&lt;'],
	[/>/g, '&gt;'],
	[/{/g, '&#123;'],
	[/}/g, '&#125;'],
];

So I guess the < character should only be replaced inside code blocks as mentioned in the comment, but using < leads to the same error because somewhere during the preprocess it gets replaced with < again.

[josephg]

I wonder if mdsvex should interpret < and { characters followed by a space literally, generally well-formatted HTML/svelte doesn’t do this and handling this in a special way would allow a number of obvious cases to work, such as this one: #113 (comment) (tl;dr: writing foo < bar to make some didactic point)

The commonmark specification has a list of rules for what constitutes legal tags. Anything that isn’t a valid tag is escaped. This example shows a < followed by a space is not considered a valid tag name. Eg, < a> encodes to < a>. (As it does in this comment.)

Commonmark has a test suite of JSON content. We should get that test suite passing in mdsevx.

[josephg]

Its awful but double escaping seems to work:

5 < 10

It doesn’t work in the playground though. For some reason & makes the playground hit another bug and error with Document is not defined