I am trying to convert a markdown document to HTML, using pandoc. I cannot get the HTML output to create the table of contents correctly.
Issue:
I have added a table of contents to the markdown doc, where clicking on each header takes the reader to the relevant section. I am using the format below, where clicking on 'Header Title' will send the reader to the section 'header' in the document:
[Header Title](#header)
I tried to convert this to HTML using the pandoc command
pandoc -i input.md -f markdown -t html -o input.html
This creates a valid HTML file I can open in Firefox, and the items in the table of contents show up as links - but when I click them, nothing happens (I am expecting it to jump to the relevant section)
This happens when I use either markdown or markdown_github as the input format (-i in pandoc)
Question:
How can I get the table of contents to show the expected behavior in HTML?
Or is the concept of 'table of contents' a wrong approach to HTML, and I should change my markdown code?
Apologies if I am going about this the wrong way, I have no experience with HTML / web documents.
I found a couple of similar questions but they seemed to be specific to other programming languages / tools, so any help how I can achieve this with markdown / pandoc is much appreciated.
I am using pandoc 1.19.2.4 on Ubuntu.
Example markdown:
- [Chapter 1](#chapter-1)
- [1. Reading a text file](#1-reading-a-text-file)
## Chapter 1
This post focuses on standard text processing tasks such as reading files and processing text.
### 1. Reading a text file
Reading a file.
Looking at your markdown file, you have used #1-reading-a-text-file as the id for the 1st subheading.
While converting it to HTML, the following line is generated for the subheading:
<h3 id="reading-a-text-file">1. Reading a text file</h3>
The problem is the mismatch of "#1" which is present in the table of contents, but not in the heading.
My guess is that pandoc does not allow HTML id to start with a number.
Changing the table of contents to the following should work:
- [Chapter 1](#chapter-1)
- [1. Reading a text file](#reading-a-text-file)
I use {% include text.md %} in my posts to include some often typed paragraphs.
I have a Generator plugin that makes some text replacement in post contents.
However, the text inside the included files (e.g. text.md) is not processed by this plugin.
How can I run the plugin after includes are performed but before html is rendered? Or how could I do things differently to make it work?
Jekyll processes a site in distinct "phases".
reset >> read >> generate >> render >> cleanup >> write
A Generator subclass is generally used to "generate" objects (Pages or Documents) that are then rendered based on the prioritydefined for the generator.
An include tag (or any Liquid constructs) is "rendered" in the subsequent phase.
Unfortunately, you cannot alter the "raw content" of a file in the middle of the rendering phase.
Jekyll provides you with just a :pre_render hook to manipulate unrendered content of a file.
I use jekyll to write post and show it in GitHub-pages. My source file is written with markdown.
How can I insert formula into the markdown file?
I don't want to save the formula into an image and load the image in markdown file. I actually want to write latex formula in markdown file directly.
Since resources online have changed regarding this question, here's an update on supporting LateX with GitHub Pages.
Note that the closest to Latex rendering without exporting as images and natively supporting it on your Jekyll site would be to use MathJax.
MathJax is actually recommended in Jekyllrb docs for math support, with Kramdown, it also converts it from LaTeX to PNG, more details on it here at the Kramdown documentation
Option 1: Write your equation in MathURL and embed it.
You could write the equation with MathURL, then generate a url that permanently points to the equation, and display this in an <iframe> tag. However, this will stop working if MathURL goes offline.
Option 2: Implement jsMath
jsMath will allow almost LateX like syntax and will be supported in your blog if you have set it up correctly, there is extensive documentation on this.
Option 3: Mathjax (by far the easiest in my opinion)
Many sites have mentioned that Mathjax is considered a successor of jsMath, and is much easier to implement with Jekyll. MathJax is also used by mathematics.stackexchange.com too!
Step 1: Have your site load the script in sites where you want to display math. (usually done in the header)
Optional: Check your markdown parser in _config.yml. redcarpet or kramdown is suggested in this example. Certain parsers like discount will interfere with the syntax but I have a solution below.
Step 2: Write your equations.
Quoting this tutorial by Gaston Sanchez:
MathJax does not have the exactly same behavior as LaTeX. By default,
the tex2jax preprocessor defines the LaTeX math delimiters, which are
\(...\) for in-line math, and \[...\] for displayed equations. It
also defines the TeX delimiters $$...$$ for displayed equations, but
it does not define $...$ as in-line math delimiters.
Read the documentation on the syntax for more details.
Note: Using the raw liquid tag to ensure Markdown parsers do not interfere with MathJax syntax.
While you could escape backslashes (e.g. \\[ \frac{1}{n^{2}} \\])to
ensure they are parsed properly, as described by Chistopher Poole's
tutorial, this is not always intuitive and looks complicated. A
simpler solution would be to use the raw liquid tag to ensure the
text is ignored by the Markdown processor and directly output as a
static html. This is done with {% raw %}and also {% endraw %}
Here is a code sample:
{% raw %}
$$a^2 + b^2 = c^2$$ --> note that all equations between these tags will not need escaping!
{% endraw %}
Lastly also ensure that the fonts support displaying LateX as some have issues like font size being too small. Alternatively here are some additional methods like Google Charts and MathML discussed in the latex StackExchange sister site.
If you used Jekyll in your GitHub pages, you can add
<script type="text/x-mathjax-config">
MathJax.Hub.Config({
tex2jax: {
skipTags: ['script', 'noscript', 'style', 'textarea', 'pre'],
inlineMath: [['$','$']]
}
});
</script>
<script src="https://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS-MML_HTMLorMML" type="text/javascript"></script>
in the file _includes/head.html, and then your GitHub Pages site will support MathJax
The easiest way to do this right now is to use the KaTeX auto-render extension.
Simply drop the following into your <head>:
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/katex#0.10.2/dist/katex.min.css" integrity="sha384-yFRtMMDnQtDRO8rLpMIKrtPCD5jdktao2TV19YiZYWMDkUR5GQZR/NOVTdquEx1j" crossorigin="anonymous">
<script defer src="https://cdn.jsdelivr.net/npm/katex#0.10.2/dist/katex.min.js" integrity="sha384-9Nhn55MVVN0/4OFx7EE5kpFBPsEMZxKTCnA+4fqDmg12eCTqGi6+BB2LjY8brQxJ" crossorigin="anonymous"></script>
<script defer src="https://cdn.jsdelivr.net/npm/katex#0.10.2/dist/contrib/auto-render.min.js" integrity="sha384-kWPLUVMOks5AQFrykwIup5lo0m3iMkkHrD0uJ4H5cjeGihAutqP0yW0J6dpFiVkI" crossorigin="anonymous" onload="renderMathInElement(document.body);"></script>
Note that this assumes the following delimiters appear in your HTML:
$$\LaTeX code$$ (for display)
\\[\LaTeX code\\] (also for display)
\\(\LaTeX code\\) (for inline)
Note, if using Jekyll, you will need to have the following in your _config.yml:
markdown: kramdown
kramdown:
math_engine: katex
WARNING: Do not use math_engine: mathjax. It will break this by automatically removing the LaTeX delimiters.
Unfortunately most answers here are outdated nowadays. Github renders your markdown files using kramdown . Annoyingly kramdown defines math content differently from other markdown variants. In kramdown inline math is written using $$ as delimiter like text $$ E = mc^2 $$ text. Display math is also written using $$ delimiter, but it must be separated from the text by a blank line
text
$$\begin{aligned}
E = mc^2
\end{aligned}$$
text
Kramdown will render the inline math as \( E = mc^2 \) and the display math as
\[\begin{aligned}
E = mc^2
\end{aligned}\]
in your output HTML. These are also the delimiters used by mathjax as default. Therefore to configure MathJax 3 for github pages it is enough to add
<script id="MathJax-script" async src="https://cdn.jsdelivr.net/npm/mathjax#3/es5/tex-mml-chtml.js"></script>
to the file _includes/head-custom.html. You don't need to create or modify the _config.yml file.
I recommend you to use MathJax 3 over KaTeX, because MathJax 3 is not much slower anymore than KaTeX (see https://www.intmath.com/cg5/katex-mathjax-comparison.php) and supports more features (E.g. KaTex cannot handle \label and \eqref (see https://github.com/KaTeX/KaTeX/issues/2003))
If you still want to use https://katex.org/docs/autorender.html you must add
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/katex#0.15.6/dist/katex.min.css" integrity="sha384-ZPe7yZ91iWxYumsBEOn7ieg8q/o+qh/hQpSaPow8T6BwALcXSCS6C6fSRPIAnTQs" crossorigin="anonymous">
<script defer src="https://cdn.jsdelivr.net/npm/katex#0.15.6/dist/katex.min.js" integrity="sha384-ljao5I1l+8KYFXG7LNEA7DyaFvuvSCmedUf6Y6JI7LJqiu8q5dEivP2nDdFH31V4" crossorigin="anonymous"></script>
<script defer src="https://cdn.jsdelivr.net/npm/katex#0.15.6/dist/contrib/auto-render.min.js" integrity="sha384-+XBljXPPiv+OzfbB3cVmLHf4hdUFHlWNZN5spNQ7rmHTXpd7WvJum6fIACpNNfIR" crossorigin="anonymous"
onload="renderMathInElement(document.body);"></script>
to the file _includes/head-custom.html. You don't need to create or modify the _config.yml file.
Note: I tried to use github flavored markdown renderer instead of the default renderer for github pages by setting markdown: GFM in the the _config.yml file. This would give you additional features like autolinks ( see https://github.community/t/github-pages-autolinks-fail/129713/4 ) and the more common $ delimiter for inline math and $$ delimiter for display math (https://github.blog/2022-05-19-math-support-in-markdown/) as it is supported by https://pandoc.org/. However the GFM markdown renderer from github has still many, many problems with math section making it unusable (https://nschloe.github.io/2022/05/20/math-on-github.html).
A while ago I created xhub, a browser extension that allows you to use math in github pages.
Cons:
You have to install the extension.
Pros:
No need to set up any workflow.
Just edit your markdown as usual and use
Display math:
```math
e^{i\pi} + 1 = 0
```
and inline math $`a^2 + b^2 = c^2`$.
(Syntax just like on GitLab.)
Works well on light and dark background.
You can even copy-and-paste the math!
Perhaps worth checking out.
I would like this to be a comment on daviewales answer but I do not have enough reputation unfortunately. My understanding of that answer is to copy the 3 lines of code into the file <your_repo>.github.io\_site\<postname>\index.html. However, that file seems to get updated each time the corresponding <postname>.md is edited. Is there a more elegant way to always get those lines of code automatically added to the html file, without having to manually edit it every time I want to check an equation?
EDIT:
I think this is one solution to the above problem:
What ended up working for me was based off of PeaShooter's response. I made a folder _includes within my _posts folder, and then populated it with a file head.html containing the code from PeaShooter's answer. Then, in the top line of the post below the YAML front matter (i.e. below the second --- line) I put the code {% include_relative _includes/head.html %}
Note that it was important to make the _includes folder not in base folder <your_repo>.github.io, but within the _posts folder. While placing _includes in the base folder did automatically generate the equation, it ruined the formatting for the rest of the website.
The best way right now IMO is to use the MathJax backend (which is part of kramdown, i.e. available on GitHub Pages) and then use KaTeX on the frontend for rendering. KaTeX is more lightweight and faster than MathJax, which makes it a better fit for a blog theme.
I'm using this technique with great success for my Jekyll theme Hydejack. Feel free to use it on your own site, by doing the following:
In config.yml, set the math engine to mathjax:
kramdown:
math_engine: mathjax
Add KaTeX to your site and also make sure the following code runs sometime after it has loaded.
const mathBlocks = document.querySelectorAll('script[type^="math/tex"]');
Array.from(mathBlocks).forEach((el) => {
const tex = el.textContent.replace("% <![CDATA[", "").replace("%]]>", "");
el.outerHTML = window.katex.renderToString(tex, {
displayMode: el.type === "math/tex; mode=display",
});
});
The actual code I'm using is slightly more complicated. You can check it out on GitHub.
Some of the answers are a bit complicated or even outdated so here's a recent solution that works well for me. You can solve the problem using layouts.
Create a folder _layouts to the folder from which you publish (for example docs/).
Create default.html. This will be the layout for all your pages. If you have just started your page, you can use this as a template for the default.html file:
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>{{ page.title }}</title>
</head>
<body>
{{ content }}
</body>
</html>
Then add this script before </html>:
<script
src="https://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS-MML_HTMLorMML"
type="text/javascript">
</script>
I had the problem that I was using minima theme. So if I applied the change above I lost my theme in my posts. I went to the github repo and copied whatever they had in default.html and added the script above before </html> and it worked!
I found out the answer here.
I am building an octopress blog. In that blog, a number of entries have footnotes. The markdown files currently denote a footnote like so:
"This is the main text <footnote>and this is the footnote</footnote> where
we speak of main-text things"
What I want to do is extract the footnotes from the body text and then have access to both the main text AND the footnotes as variables in the layout.
I've made some progress with this by creating a filter but it doesn't work very well because filters always output directly on return and I need to format the footnotes.
Would a generator be more appropriate? A converter? Should I not be using liquid tags at all in this case?
Filters make the most sense to me. Is there a way to get the return value of a filter without it printing to the screen? I currently use this:
{{ content | footnotes }}
But that just dumps the array as one big, unformatted array. If it isn't blindingly obvious already, I'm just getting started with Liquid and I'm a little confused.
Depending on your markdown parser you could just write the footnotes normally in the markdown. This is what I'm using on my blog. This is my config in the _config.yml file:
markdown: rdiscount
rdiscount:
extensions:
- autolink
- footnotes
- smart
Then I just use footnotes by using [^1] to specify the footnote and
[^1]: My footnote
To show it at the bottom of the screen.
Or are you trying to show footnotes at some other part of the screen and not at the bottom of the post?
I convert a book which is written in DocBook into a single page HTML. The HTML contains a TOC:
<div class="toc">
<dl>
<dt><span class="preface">Preface</span></dt>
<dt><span class="chapter"><a href="#installation-und-versionsauswahl">1. Version Selection and
Installation</a></span></dt>
[...]
I'd like to use kindlegen to convert the HTML into a file I can use with a Kindle. That works without a problem. BUT the TOC is not recognized as a TOC. The Kindle user can't access the TOC directly with the TOC button.
What do I have to change that kindlegen recognize the TOC in my HTML file?
I'd recommend reading the official Kindle publishing guidlines from Amazon.
AFAIK kindlegen can't do that, you need a proper NCX file or an OPF with properly set TOC setting.
See also this short tutorial.
In case useful, I knocked up a quick PHP script to generate very basic NCX and OPF files to support the TOC without having to break up the document. I wrote the script based on a MS Word documented saved as HTML (so it is hard coded to use those style names). Just noting it here in case useful to anyone who comes along this post in the future. http://alankent.me/2016/03/05/creating-a-kindle-book-using-microsoft-word-quick-note/