Enhancement: Dynamic title attribute on Markdown Footnote links

[edent]

Impacted plugin

Jetpack

What

Footnote links' titles say "Read footnote." This would make the attribute display the content of the footnote.

How

At the moment, if a user hovers over a footnote, the title attribute displays this tool tip:

---

I think it would be nice if JetPack showed users the full text of the footnote. For example:

---

This is controlled by :

jetpack/projects/plugins/jetpack/_inc/lib/markdown/extra.php

Line 3020 in d7a6569

function _appendFootnotes_callback($matches) {

Specifically:

if ($this->fn_link_title != "") {
	$title = $this->fn_link_title;
	$title = $this->encodeAttribute($title);
	$attr .= " title=\"$title\"";
}

The change is relatively straightforward:

if ($this->fn_link_title != "") {
	$title = trim( wp_strip_all_tags($this->footnotes[$node_id], true) );
	$title = $this->encodeAttribute($title);
	$attr .= " title=\"$title\"";
}

That takes the text of the footnote, sanitises it, and adds it as the title element.

This builds on the work I did in #21371