According to the web component spec, a dash is required, which breaks md parsing

[rodsimpson]

If you are using web components in your html / md, you must have a dash. For example:

Invalid:
<mycomponent></mycomponent>

Valid:
<my-component></my-component>

The former case stops further parsing of markdown. For example:

Works:
<mycomponent></mycomponent>
# header

Doesn't work:
<my-component></my-component>
# header

In the second case, # header is not converted to an H1 tag, but it should be.

[pablotheissen]

The following seems to fix it:

Line 676:
- if (preg_match('/^<(\w*)(?:[ ]*'.$this->regexHtmlAttribute.')*[ ]*(\/)?>/', $Line['text'], $matches))
+ if (preg_match('/^<(\w[\w-]*)(?:[ ]*'.$this->regexHtmlAttribute.')*[ ]*(\/)?>/', $Line['text'], $matches))

Ditto on line 1277:
- if ($Excerpt['text'][1] !== ' ' and preg_match('/^<\w*(?:[ ]*'.$this->regexHtmlAttribute.')*[ ]*\/?>/s', $Excerpt['text'], $matches))
+ if ($Excerpt['text'][1] !== ' ' and preg_match('/^<\w[\w-]*(?:[ ]*'.$this->regexHtmlAttribute.')*[ ]*\/?>/s', $Excerpt['text'], $matches))

Line 1261:
- if ($Excerpt['text'][1] === '/' and preg_match('/^<\/\w*[ ]*>/s', $Excerpt['text'], $matches))
- if ($Excerpt['text'][1] === '/' and preg_match('/^<\/\w[\w-]*[ ]*>/s', $Excerpt['text'], $matches))

This changed regex allows custom element names such as <valid-tag> but not <-notvalid>. I have not tested the code against all the other unicode characters mentioned in above link.

-- edit: after studying the WHATWG document again: <valid-.> as well as <valid-ℬ> should be valid but would make the RegExp way more complex.

-- edit2: changed the regexp to validate as well as and (line 1261) which didn't work before.

[PhrozenByte]

@pablotheissen: Don't make it overcomplicated, Parsedown is no HTML validator, it's just about matching HTML elements, not about validating them. So, just add the . next to the - as allowed char and this should be good to go.

[taufik-nurrohman]

What about namespaces? Example <foo:bar baz:qux="xyz">

/<[\w:.-]+(\s[^<>]*?)?>/

[aidantwoods]

Provided that you include a newline between the HTML and the markdown following it this should work as expected in the next release :)