bradhowes / notebookjs-katex

Filter for IPython source files that converts $..$ and $$..$$ blocks in Markdown cells into KaTeX math HTML.

Overview

IPython Markdown cells can format LaTeX math expressions between $...$ (inline) or $$...$$ (block) delimiters. This works great when editing and viewing within a Jupyter process. However, when converting the source *.ipynb file to HTML using the otherwise excellent notebookjs package the math expressions do not appear -- notebookjs does not currently support expansion of $...$ and $$...$$ expressions into math HTML renderings.

NOTE: currently the delimiters are hard–coded. Customizing this is work for a future release.

This NPM package provides a simple filter for IPython source which when run before notebookjs's render process will properly generate inline and block math HTML expressions using the KaTeX package. I use this to perform server-side math expression rendering for my blog, Keystroke Countdown. The post Metalsmith Plugins for Server-side KaTeX Processing talks about the implementation of this package as well as a Remarkable plugin that does similar processing for Markdown text.

To Use

Install this package using npm:

% npm install [-s] notebookjs-katex

Assuming you already have notebookjs installed, one way for using this would like so, just prior to using notebookjs to parse and render HTML:

var KatexFilter = require("notebookjs-katex");
var kf = new KatexFilter();

var ipynb = JSON.parse(fs.readFileSync('/path/to/notebook.ipynb'));
kf.expandKatexInNotebook(ipynb);

var notebook = notebookjs.parse(ipynb);
var html = notebook.render().outerHTML;

Configuration

The KatexFilter constructor takes an optional configuration object which will be given to the KaTeX render method. See the docs for details. Note that KatexFilter always sets throwOnError to false, and displayMode will be set depending on the delimiters surrounding the math expression.

Dependencies

• jsonpath -- used to isolate the Markdown cells in an IPython notebook JSON file.
• KaTeX -- performs the rendering of the LaTeX commands.

Tests

There are a set of Vows in index.test.js. To run:

% npm test

NOTE: if this fails, there may be a path issue with vows executable. See package.json.