Page Toc changes HTML rendering of horizontal rule

[shankar2k]

I installed this plugin and found that my implementation of multiple columns (based on this recipe) stopped working. After some digging, I discovered the reason for this is that this plugin changes the HTML rendering of the markdown --- from <hr /> to <hr>. Is there a reason for this change? Can it be documented somewhere?

[pamtbaau]

Did some digging...

The issue has been introduced in v3.0.0 when HTML5 library is being replaced by PHP DOMDocument class.

When saving a DOMDocument into HTML, the <hr /> is being replaced with <hr> conform the HTML specs.

In the following code line, $markup contains <hr /> before executing the code line and contains <hr> after.

grav-plugin-page-toc/classes/MarkupFixer.php

Line 79 in f8da91d

$markup = $domDocument->saveHTML($domDocument->getElementsByTagName('page-toc')->item(0));

I'll add a note to the recipe in the docs.

[shankar2k]

Thank you! Should the rendering of the markdown --- be changed to <hr> in general, to conform with HTML specs? Or is that happening in code provided elsewhere (e.g., Twig)?

[pamtbaau]

Should the rendering of the markdown --- be changed to <hr> in general, to conform with HTML specs?

The rendering of Markdown happens by Grav's external library Parsedown, which tries to be CommonMark Spec compliant. According to CommonMark, Thematic Breaks should be rendered as <hr />.

It is the PHP DOMDocument library, used by Page Toc, that converts <hr /> generated by Parsedown, into <hr>.

I don't think CommonMark is going to change its specs, neither the Markdown parser being used...

So, when using the recipe you are referring to, filter |split('<hr />') should be replaced by |split('<hr>') when using plugin Page Toc.