Iterate over links in markdown content in Jekyll - jekyll

Question

I am wondering is it possible in Jekyll to iterate over elements of the processed page content in Jekyll Liquid filters, in particular to iterate over all the <a> elements on the page and get their their content and href attributes.
I'd like to be able to have something in a page like
<ul>
{% for link in content.links %}
<li>so something here with {{link.contents}} and {{link.href}}.</li>
{% endfor %}
</ul>
Is there any native feature or plugin that would allow something like this? It does not have to be compatible with Github Pages.
Edit:
I ended up making a modified version of the plugin Christian suggested in their answer that captures reference-style links as well and excludes images.
Jekyll::Hooks.register :site, :pre_render do |site|
site.collections.each do |collection, files|
if files.docs.any?
files.docs.each do |file|
links = []
inline_regex = /[^!]\[([^\]]+)\]\(([^)]+)\)/
referenced_regex = /\[([^\]]+)\](?:\[([^\]]+)\])?[^:]/
references_regex = /\[([^\]]+)\]: ?(.+)/
file.content.scan(inline_regex).each do |match|
if match.length == 2
links << {
"text" => match[1],
"ref" => match[1],
"link_url" => match[2]
}
end
end
file.content.scan(referenced_regex).each do |d_match|
if d_match.length == 2
link = { "text" => d_match[0], "ref" => d_match[1] }
elsif d_match.label == 1
link = { "text" => d_match[0], "ref" => d_match[0] }
end
file.content.scan(references_regex).each do |s_match|
if s_match[0] == link["ref"] and s_match[1]
links << link.merge!({"url" => s_match[1]})
end
end
end
file.merge_data!({"links" => links})
end
end
end
end

Answer 1

You can loop over a dynamically generated front matter attribute.
The page front matter will contain the link texts and URLs matched by a regular expression.
Jekyll include file
To avoid repetitions, I have created an include file for your code snippet in _includes\link_info.html.
<ul>
{% for link in page.links %}
<li>so something here with {{link.link_text}} and {{link.link_url}}.</li>
{% endfor %}
</ul>
You can insert the include file code in your layout(s) or each post individually. A sample post could be:
---
layout: default
title: "Your page title"
---
{% include link_info.html %}
[google](https://www.google.com)
Plugin to generate the links front matter attribute on each page
I have created a plugin using the pre-render hook in _plugins\links_in_documents.rb:
# This plugin dynamically adds the frontmatter attribute. This covers documents in all collections including posts.
# It does not cover non-collection pages like index, search or 404 pages, on which attributes have to be set manually.
Jekyll::Hooks.register :site, :pre_render do |site|
site.collections.each do |collection, files|
if files.docs.any?
files.docs.each do |file|
# empty page.links array for the particular file
links = []
# Regex from https://stackoverflow.com/questions/9268407/how-to-convert-markdown-style-links-using-regex
# Any other link types would require adjusting the regex to match the different types.
regex = /\[([^\]]+)\]\(([^)]+)\)/
match = file.content.match(regex)
# insert any link into the array
if match
## debug output on jekyll serve
# puts "link #{match} found in #{file.relative_path}"
links << { "link_text" => match[1], "link_url" => match[2] }
end
# merges data in the page front matter
file.merge_data!({"links" => links})
end
end
end
end