Update CDN URLs, add option for local libs and SRI attributes

docs/source/customizing.ipynb

@@ -11,7 +11,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "Under the hood, nbconvert uses [Jinja templates](https://jinja2.readthedocs.io/en/latest/intro.html) to specify how the notebooks should be formatted. These templates can be fully customized, allowing you to use nbconvert to create notebooks in different formats with different styles as well."
+    "Under the hood, nbconvert uses [Jinja templates](http://jinja.pocoo.org/docs/) to specify how the notebooks should be formatted. These templates can be fully customized, allowing you to use nbconvert to create notebooks in different formats with different styles as well."
    ]
   },
   {

nbconvert/exporters/html.py

@@ -6,7 +6,7 @@
 
 import os
 
-from traitlets import default, Unicode
+from traitlets import default, Unicode, Bool
 from traitlets.config import Config
 
 from nbconvert.filters.highlight import Highlight2HTML
@@ -26,6 +26,14 @@ class HTMLExporter(TemplateExporter):
     anchor_link_text = Unicode(u'¶',
         help="The text used as the text for anchor links.").tag(config=True)
 
+    use_local_libs = Bool(False,
+        help="If True, use local folder libs/ instead of fetching resources from CDN"
+    ).tag(config=True)
+
+    use_sri_attr = Bool(False,
+        help="If True, use SRI hashes for sub-resources, i.e. external javascript and CSS"
+    ).tag(config=True)
+
     @default('file_extension')
     def _file_extension_default(self):
         return '.html'
@@ -88,11 +96,17 @@ def process_attachments(self, nb, output):
         return output
 
     def from_notebook_node(self, nb, resources=None, **kw):
+        resources = self._init_resources(resources)
+        if 'reveal' not in resources:
+            resources['reveal'] = {}
+        resources['reveal']['use_local_libs'] = self.use_local_libs
+        resources['reveal']['use_sri_attr'] = self.use_sri_attr
+
         langinfo = nb.metadata.get('language_info', {})
         lexer = langinfo.get('pygments_lexer', langinfo.get('name', None))
         highlight_code = self.filters.get('highlight_code', Highlight2HTML(pygments_lexer=lexer, parent=self))
         self.register_filter('highlight_code', highlight_code)
 
-        output, resources = super(HTMLExporter, self).from_notebook_node(nb, resources, **kw)
+        output, resources = super(HTMLExporter, self).from_notebook_node(nb, resources=resources, **kw)
         att_output = self.process_attachments(nb, output)
         return att_output, resources

nbconvert/exporters/slides.py

@@ -100,7 +100,7 @@ def _reveal_url_prefix_default(self):
             warn("Please update RevealHelpPreprocessor.url_prefix to "
                  "SlidesExporter.reveal_url_prefix in config files.")
             return self.config.RevealHelpPreprocessor.url_prefix
-        return 'https://cdnjs.cloudflare.com/ajax/libs/reveal.js/3.5.0'
+        return 'https://cdnjs.cloudflare.com/ajax/libs/reveal.js/3.7.0'
 
     reveal_theme = Unicode('simple',
         help="""
@@ -130,7 +130,7 @@ def _reveal_url_prefix_default(self):
     ).tag(config=True)
 
     require_js_url = Unicode(
-        "https://cdnjs.cloudflare.com/ajax/libs/require.js/2.1.10/require.min.js",
+        "https://cdnjs.cloudflare.com/ajax/libs/require.js/2.3.6/require.min.js",
         help="""
         URL to load require.js from.
 
@@ -139,7 +139,7 @@ def _reveal_url_prefix_default(self):
     ).tag(config=True)
 
     jquery_url = Unicode(
-        "https://cdnjs.cloudflare.com/ajax/libs/jquery/2.0.3/jquery.min.js",
+        "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js",
         help="""
         URL to load jQuery from.
 

nbconvert/templates/html/full.tpl

@@ -1,6 +1,18 @@
 {%- extends 'basic.tpl' -%}
 {% from 'mathjax.tpl' import mathjax %}
+{% from 'urls.tpl' import all_urls, all_attr %}
 
+{% if resources['reveal']['use_local_libs'] == true %}
+  {% set urls = all_urls.local_paths %}
+{% else %}
+  {% set urls = all_urls.default_cdn %}
+{% endif %}
+
+{% if resources['reveal']['use_sri_attr'] == true %}
+  {% set attr = all_attr.sri_attr %}
+{% else %}
+  {% set attr = all_attr.empty_attr %}
+{% endif %}
 
 {%- block header -%}
 <!DOCTYPE html>
@@ -11,8 +23,8 @@
 {% set nb_title = nb.metadata.get('title', '') or resources['metadata']['name'] %}
 <title>{{nb_title}}</title>
 
-<script src="https://cdnjs.cloudflare.com/ajax/libs/require.js/2.1.10/require.min.js"></script>
-<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/2.0.3/jquery.min.js"></script>
+<script src="{{urls.require_js_url}}" {{attr.require_js_attr}}></script>
+<script src="{{urls.jquery_url}}" {{attr.jquery_attr}}></script>
 
 {% block ipywidgets %}
 {%- if "widgets" in nb.metadata -%}
@@ -87,7 +99,7 @@ div#notebook-container{
 <link rel="stylesheet" href="custom.css">
 
 <!-- Loading mathjax macro -->
-{{ mathjax() }}
+{{ mathjax(urls) }}
 {%- endblock html_head -%}
 </head>
 {%- endblock header -%}

nbconvert/templates/html/mathjax.tpl

@@ -1,6 +1,6 @@
-{%- macro mathjax(url='https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.5/latest.js?config=TeX-AMS_HTML') -%}
+{%- macro mathjax(urls) -%}
     <!-- Load mathjax -->
-    <script src="{{url}}"></script>
+    <script src="{{urls.mathjax_url}}" {{urls.mathjax_attr}}></script>
     <!-- MathJax configuration -->
     <script type="text/x-mathjax-config">
     MathJax.Hub.Config({

nbconvert/templates/html/urls.tpl

@@ -0,0 +1,56 @@
+{# default configuration #}
+{% set cdn1_base = 'https://cdnjs.cloudflare.com/ajax/libs/' %}
+{% set default_cdn      = {
+  'mathjax_url'      : cdn1_base ~ 'mathjax/2.7.5/latest.js?config=TeX-AMS_HTML',
+  'require_js_url'   : cdn1_base ~ 'require.js/2.3.6/require.min.js',
+  'jquery_url'       : cdn1_base ~ 'jquery/3.3.1/jquery.min.js',
+  'reveal_js_url'    : cdn1_base ~ 'reveal.js/3.7.0/js/reveal.min.js',
+  'font_awesome_url' : cdn1_base ~ 'font-awesome/4.7.0/css/font-awesome.css',
+  } %}
+
+{# alternative external resources - not yet implemented as switch #}
+{% set cdn2_base = 'https://cdn.jsdelivr.net/npm/' %}
+{% set alternative_cdn      = {
+  'mathjax_url'      : cdn2_base ~ '[email protected]/unpacked/MathJax.min.js',
+  'require_js_url'   : 'https://requirejs.org/docs/release/2.3.6/minified/require.js',
+  'jquery_url'       : cdn2_base ~ '[email protected]/dist/jquery.min.js',
+  'reveal_js_url'    : cdn2_base ~ '[email protected]/js/reveal.min.js',
+  'font_awesome_url' : 'https://stackpath.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css',
+  } %}
+
+{# set local paths for resources #}
+{% set libs_dir  = 'libs/' %}
+{% set local_paths      = {
+  'mathjax_url'      : libs_dir ~ 'mathjax/2.7.5/latest.js?config=TeX-AMS_HTML',
+  'require_js_url'   : libs_dir ~ 'require.min.js',
+  'jquery_url'       : libs_dir ~ 'jquery.min.js',
+  'reveal_js_url'    : libs_dir ~ 'reveal.min.js',
+  'font_awesome_url' : libs_dir ~ 'font-awesome.css',
+  } %}
+
+{% set all_urls = {
+  'default_cdn'     : default_cdn ,
+  'alternative_cdn' : alternative_cdn ,
+  'local_paths'     : local_paths ,
+  } %}
+
+{% set empty_attr     = {
+  'mathjax_attr'      : '',
+  'require_js_attr'   : '',
+  'jquery_attr'       : '',
+  'reveal_js_attr'    : '',
+  'font_awesome_attr' : '',
+  } %}
+
+{% set sri_attr     = {
+'mathjax_attr'      : 'integrity="sha256-WUED7NFzpsmHtLO7bswSz4JSfkhE+cD4ncKeOznwFSY= sha384-paYjEtNXu9X/q6SBQB9EivI88vKEc/TiZWUaaH5j2Hi4vAOnVYmcahbzUELr3LHw sha512-BlZeGCIONWMdv9uCBB3I3hpY94r8I2e4DdNxyl4OOHYg0Y/LwwWDC4ioJr9vRaLNHwQG0oHiFdmqt7UaTCAZ0A==" crossorigin="anonymous"',
+'require_js_attr'   : 'integrity="sha256-1fEPhSsRKlFKGfK3eO710tEweHh1fwokU5wFGDHO+vg= sha384-38qS6ZDmuc4fn68ICZ1CTMDv4+Yrqtpijvp5fwMNdbumNGNJ7JVJHgWr2X+nJfqM sha512-c3Nl8+7g4LMSTdrm621y7kf9v3SDPnhxLNhcjFJbKECVnmZHTdo+IRO05sNLTH/D3vA6u1X32ehoLC7WFVdheg==" crossorigin="anonymous"',
+'jquery_attr'       : 'integrity="sha256-FgpCb/KJQlLNfOu91ta32o/NMZxltwRo8QtmkMRdAu8= sha384-tsQFqpEReu7ZLhBV2VZlAu7zcOV+rXbYlF2cqB8txI/8aZajjp4Bqd+V6D5IgvKT sha512-+NqPlbbtM1QqiK8ZAo4Yrj2c4lNQoGv8P79DPtKzj++l5jnN39rHA/xsqn8zE9l0uSoxaCdrOgFs6yjyfbBxSg==" crossorigin="anonymous"',
+'reveal_js_attr'    : 'integrity="sha256-Xr6ZH+/kc7hDVReZLO5khBknteLqu5oen/xnSraXrVk= sha384-YSZJq04Xw1k1QeTgkujYtdAjgN/sspQx01Qx4JPksOst7V7juBOa/XBwsIK+mJ7c sha512-47qp+bUV262nwngjB+lBR1txpTKevoQKlz3d1+0uvu6Zly3Q+Y+tR19xDDk4NnutJ9vu6uojPXQS4S3sOB06qw==" crossorigin="anonymous"',
+'font_awesome_attr' : 'integrity="sha256-NuCn4IvuZXdBaFKJOAcsU2Q3ZpwbdFisd5dux4jkQ5w= sha384-FckWOBo7yuyMS7In0aXZ0aoVvnInlnFMwCv77x9sZpFgOonQgnBj1uLwenWVtsEj sha512-5A8nwdMOWrSz20fDsjczgUidUBR8liPYU+WymTZP1lmY9G6Oc7HlZv156XqnsgNUzTyMefFTcsFH/tnJE/+xBg==" crossorigin="anonymous"',
+  } %}
+
+{% set all_attr = {
+  'empty_attr'  : empty_attr,
+  'sri_attr'    : sri_attr,
+  } %}