Add support for extra packages

README.md

@@ -33,6 +33,7 @@ mathjax:
   normal_width: 0.6 # relative normal (monospace) width
   append_css: true # add CSS to pages rendered by MathJax
   every_page: false # if true, every page will be rendered by MathJax regardless the `mathjax` setting in Front-matter
+  packages: # extra packages to load
   extension_options: {}
     # you can put your extension options here
     # see http://docs.mathjax.org/en/latest/options/input/tex.html#tex-extension-options for more detail

lib/filter.js

@@ -7,7 +7,7 @@ const { SVG } = require('mathjax-full/js/output/svg.js');
 const { LiteAdaptor } = require('mathjax-full/js/adaptors/liteAdaptor.js');
 const { RegisterHTMLHandler } = require('mathjax-full/js/handlers/html.js');
 
-const { AllPackages } = require('mathjax-full/js/input/tex/AllPackages.js');
+let { AllPackages } = require('mathjax-full/js/input/tex/AllPackages.js');
 
 module.exports = function(config) {
 
@@ -26,6 +26,9 @@ module.exports = function(config) {
     //
     //  Create input and output jax and a document using them on the content from the HTML file
     //
+    if (Array.isArray(config.packages)) {
+      AllPackages = AllPackages.concat(config.packages);
+    }
     const tex = new TeX(Object.assign({
       packages  : AllPackages,
       tags      : config.tags,