3.9.2 security release

blacklist some method from the postMessage API to prevent XSS
add note about supporting reveal.js via Slides
2025-09-09 22:20:51 +02:00 · 2020-01-31 11:11:23 +01:00 · 2020-01-31 10:59:41 +01:00 · 2020-01-30 10:15:39 +01:00 · 2020-01-29 15:11:49 +01:00 · 2020-01-29 14:51:28 +01:00
16 changed files with 850 additions and 478 deletions
--- a/2
+++ b/2
@@ -1,4 +1,4 @@
-Copyright (C) 2019 Hakim El Hattab, http://hakim.se, and reveal.js contributors
+Copyright (C) 2020 Hakim El Hattab, http://hakim.se, and reveal.js contributors

 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
--- a/README.md
+++ b/README.md
@@ -1,8 +1,11 @@
 # reveal.js [![Build Status](https://travis-ci.org/hakimel/reveal.js.svg?branch=master)](https://travis-ci.org/hakimel/reveal.js) <a href="https://slides.com?ref=github"><img src="https://s3.amazonaws.com/static.slid.es/images/slides-github-banner-320x40.png?1" alt="Slides" width="160" height="20"></a>

-A framework for easily creating beautiful presentations using HTML. [Check out the live demo](http://revealjs.com/).
+A framework for easily creating beautiful presentations using HTML. [Check out the live demo](https://revealjs.com/).

-reveal.js comes with a broad range of features including [nested slides](https://github.com/hakimel/reveal.js#markup), [Markdown contents](https://github.com/hakimel/reveal.js#markdown), [PDF export](https://github.com/hakimel/reveal.js#pdf-export), [speaker notes](https://github.com/hakimel/reveal.js#speaker-notes) and a [JavaScript API](https://github.com/hakimel/reveal.js#api). There's also a fully featured visual editor and platform for sharing reveal.js presentations at [slides.com](https://slides.com?ref=github).
+reveal.js comes with a broad range of features including [nested slides](https://github.com/hakimel/reveal.js#markup), [Markdown support](https://github.com/hakimel/reveal.js#markdown), [PDF export](https://github.com/hakimel/reveal.js#pdf-export), [speaker notes](https://github.com/hakimel/reveal.js#speaker-notes) and a [JavaScript API](https://github.com/hakimel/reveal.js#api). There's also a fully featured visual editor and platform for sharing reveal.js presentations at [slides.com](https://slides.com?ref=github).
+
+### Supporting reveal.js
+This project was started and is maintained by [@hakimel](https://github.com/hakimel/) with the help of many [contributions from the community](https://github.com/hakimel/reveal.js/graphs/contributors). The best way to support the project is to [become a paying member of Slides.com](https://slides.com/pricing)—the reveal.js presentation platform that Hakim is building.


 ## Table of contents
@@ -27,6 +30,7 @@ reveal.js comes with a broad range of features including [nested slides](https:/
 - [Touch Navigation](#touch-navigation)
 - [Lazy Loading](#lazy-loading)
 - [API](#api)
+  - [Custom Key Bindings](#custom-key-bindings)
  - [Slide Changed Event](#slide-changed-event)
  - [Presentation State](#presentation-state)
  - [Slide States](#slide-states)
@@ -49,6 +53,7 @@ reveal.js comes with a broad range of features including [nested slides](https:/
 - [Speaker Notes](#speaker-notes)
  - [Share and Print Speaker Notes](#share-and-print-speaker-notes)
  - [Server Side Speaker Notes](#server-side-speaker-notes)
+- [Plugins](#plugins)
 - [Multiplexing](#multiplexing)
  - [Master presentation](#master-presentation)
  - [Client presentation](#client-presentation)
@@ -85,7 +90,7 @@ The core of reveal.js is very easy to install. You'll simply need to download a

 Some reveal.js features, like external Markdown and speaker notes, require that presentations run from a local web server. The following instructions will set up such a server as well as all of the development tasks needed to make edits to the reveal.js source code.

-1. Install [Node.js](http://nodejs.org/) (4.0.0 or later)
+1. Install [Node.js](https://nodejs.org/) (9.0.0 or later)

 1. Clone the reveal.js repository
   ```sh
@@ -339,6 +344,19 @@ Reveal.initialize({
 	// speaker view
 	defaultTiming: 120,

+	// Specify the total time in seconds that is available to
+	// present.  If this is set to a nonzero value, the pacing
+	// timer will work out the time available for each slide,
+	// instead of using the defaultTiming value
+	totalTime: 0,
+
+	// Specify the minimum amount of time you want to allot to
+	// each slide, if using the totalTime calculation method.  If
+	// the automated time allocation causes slide pacing to fall
+	// below this threshold, then you will see an alert in the
+	// speaker notes window
+	minimumTimePerSlide: 0;
+
 	// Enable slide navigation via mouse wheel
 	mouseWheel: false,

@@ -368,6 +386,11 @@ Reveal.initialize({
 	// Number of slides away from the current that are visible
 	viewDistance: 3,

+	// Number of slides away from the current that are visible on mobile
+	// devices. It is advisable to set this to a lower number than
+	// viewDistance in order to save resources.
+	mobileViewDistance: 2,
+
 	// Parallax background image
 	parallaxBackgroundImage: '', // e.g. "'https://s3.amazonaws.com/hakim-static/reveal-js/reveal-parallax-1.jpg'"

@@ -450,7 +473,7 @@ Reveal.initialize({
 		{ src: 'plugin/markdown/markdown.js', condition: function() { return !!document.querySelector( '[data-markdown]' ); } },

 		// Syntax highlight for <code> elements
-		{ src: 'plugin/highlight/highlight.js', async: true, callback: function() { hljs.initHighlightingOnLoad(); } },
+		{ src: 'plugin/highlight/highlight.js', async: true },

 		// Zoom in and out with Alt+click
 		{ src: 'plugin/zoom-js/zoom.js', async: true },
@@ -530,7 +553,7 @@ Slides can be nested within other slides to create vertical stacks (see [Markup]
 <img src="https://static.slid.es/support/reveal.js-vertical-slides.gif" width="450">

 #### Navigation Mode
-You can finetune the reveal.js navigation behavior by using the `navigationMode` config option. Note that these options are only useful for presnetations that use a mix of horizontal and vertical slides. The following navigation modes are available:
+You can fine tune the reveal.js navigation behavior by using the `navigationMode` config option. Note that these options are only useful for presentations that use a mix of horizontal and vertical slides. The following navigation modes are available:

 | Value                         | Description |
 | :---------------------------  | :---------- |
@@ -628,6 +651,15 @@ Reveal.getProgress();       // (0 == first slide, 1 == last slide)
 Reveal.getSlides();         // Array of all slides
 Reveal.getTotalSlides();    // Total number of slides

+// Returns an array with all horizontal/vertical slides in the deck
+Reveal.getHorizontalSlides();
+Reveal.getVerticalSlides();
+
+// Checks if the presentation contains two or more
+// horizontal/vertical slides
+Reveal.hasHorizontalSlides();
+Reveal.hasVerticalSlides();
+
 // Returns the speaker notes for the current slide
 Reveal.getSlideNotes();

@@ -639,7 +671,7 @@ Reveal.isPaused();
 Reveal.isAutoSliding();

 // Returns the top-level DOM element
-getRevealElement(); // <div class="reveal">...</div>
+Reveal.getRevealElement(); // <div class="reveal">...</div>
 ```

 ### Custom Key Bindings
@@ -777,6 +809,8 @@ Embeds a web page as a slide background that covers 100% of the reveal.js width
 </section>
 ```

+Iframes are lazy-loaded when they become visible. If you'd like to preload iframes ahead of time, you can append a `data-preload` attribute to the slide `<section>`. You can also enable preloading globally for all iframes using the `preloadIframes` configuration option.
+
 #### Background Transitions

 Backgrounds transition using a fade animation by default. This can be changed to a linear sliding transition by passing `backgroundTransition: 'slide'` to the `Reveal.initialize()` call. Alternatively you can set `data-background-transition` on any section with a background to override that specific transition.
@@ -916,7 +950,7 @@ Reveal.addEventListener( 'fragmenthidden', function( event ) {
 } );
 ```

-### Code syntax highlighting
+### Code Syntax Highlighting

 By default, Reveal is configured with [highlight.js](https://highlightjs.org/) for code syntax highlighting. To enable syntax highlighting, you'll have to load the highlight plugin ([plugin/highlight/highlight.js](plugin/highlight/highlight.js)) and a highlight.js CSS theme (Reveal comes packaged with the Monokai themes: [lib/css/monokai.css](lib/css/monokai.css)).

@@ -924,7 +958,7 @@ By default, Reveal is configured with [highlight.js](https://highlightjs.org/) f
 Reveal.initialize({
 	// More info https://github.com/hakimel/reveal.js#dependencies
 	dependencies: [
-		{ src: 'plugin/highlight/highlight.js', async: true, callback: function() { hljs.initHighlightingOnLoad(); } },
+		{ src: 'plugin/highlight/highlight.js', async: true },
 	]
 });
 ```
@@ -943,6 +977,37 @@ Below is an example with clojure code that will be syntax highlighted. When the
 </section>
 ```

+#### Line Numbers & Highlights
+
+To enable line numbers, add `data-line-numbers` to your `<code>` tags. If you want to highlight specific lines you can provide a comma separated list of line numbers using the same attribute. For example, in the following example lines 4 and 8-11 are highlighted:
+
+```html
+<pre><code class="hljs" data-line-numbers="4,8-11">
+import React, { useState } from 'react';
+ 
+function Example() {
+  const [count, setCount] = useState(0);
+ 
+  return (
+    <div>
+      <p>You clicked {count} times</p>
+      <button onClick={() => setCount(count + 1)}>
+        Click me
+      </button>
+    </div>
+  );
+}
+</code></pre>
+```
+
+<img width="300" alt="line-numbers" src="https://user-images.githubusercontent.com/629429/55332077-eb3c4780-5494-11e9-8854-ba33cd0fa740.png">
+
+#### Step-by-step Highlights
+
+You can step through multiple code highlights on the same code block. Delimit each of your highlight steps with the `|` character. For example `data-line-numbers="1|2-3|4,6-10"` will produce three steps. It will start by highlighting line 1, next step is lines 2-3, and finally line 4 and 6 through 10.
+
+
+
 ### Slide number

 If you would like to display the page number of the current slide you can do so using the `slideNumber` and `showSlideNumber` configuration values.
@@ -959,9 +1024,9 @@ Reveal.configure({ slideNumber: true });
 Reveal.configure({ slideNumber: 'c/t' });

 // You can provide a function to fully customize the number:
-Reveal.configure({ slideNumber: function() {
+Reveal.configure({ slideNumber: function( slide ) {
    // Ignore numbering of vertical slides
-    return [ Reveal.getIndices().h ];
+    return [ Reveal.getIndices( slide ).h ];
 }});

 // Control which views the slide number displays on using the "showSlideNumber" value:
@@ -1037,18 +1102,38 @@ The framework has a built-in postMessage API that can be used when communicating
 <window>.postMessage( JSON.stringify({ method: 'slide', args: [ 2 ] }), '*' );
 ```

+#### postMessage Events
+
 When reveal.js runs inside of an iframe it can optionally bubble all of its events to the parent. Bubbled events are stringified JSON with three fields: namespace, eventName and state. Here's how you subscribe to them from the parent window:

 ```javascript
 window.addEventListener( 'message', function( event ) {
 	var data = JSON.parse( event.data );
-	if( data.namespace === 'reveal' && data.eventName ==='slidechanged' ) {
+	if( data.namespace === 'reveal' && data.eventName === 'slidechanged' ) {
 		// Slide changed, see data.state for slide number
 	}
 } );
 ```

-This cross-window messaging can be toggled on or off using configuration flags.
+#### postMessage Callbacks
+
+When you call any method via the postMessage API, reveal.js will dispatch a message with the return value. This is done so that you can call a getter method and see what the result is. Check out this example:
+
+```javascript
+<revealWindow>.postMessage( JSON.stringify({ method: 'getTotalSlides' }), '*' );
+
+window.addEventListener( 'message', function( event ) {
+	var data = JSON.parse( event.data );
+	// `data.method`` is the method that we invoked
+	if( data.namespace === 'reveal' && data.eventName === 'callback' && data.method === 'getTotalSlides' ) {
+		data.result // = the total number of slides
+	}
+} );
+```
+
+#### Turning postMessage on/off
+
+This cross-window messaging can be toggled on or off using configuration flags. These are the default values.

 ```javascript
 Reveal.initialize({
@@ -1180,7 +1265,7 @@ The speaker notes window will also show:
 - Current wall-clock time
 - (Optionally) a pacing timer which indicates whether the current pace of the presentation is on track for the right timing (shown in green), and if not, whether the presenter should speed up (shown in red) or has the luxury of slowing down (blue).

-The pacing timer can be enabled by configuring by the `defaultTiming` parameter in the `Reveal` configuration block, which specifies the number of seconds per slide.  120 can be a reasonable rule of thumb.  Timings can also be given per slide `<section>` by setting the `data-timing` attribute.  Both values are in numbers of seconds.
+The pacing timer can be enabled by configuring the `defaultTiming` parameter in the `Reveal` configuration block, which specifies the number of seconds per slide.  120 can be a reasonable rule of thumb.  Alternatively, you can enable the timer by setting `totalTime`, which sets the total length of your presentation (also in seconds).  If both values are specified, `totalTime` wins and `defaultTiming` is ignored.  Regardless of the baseline timing method, timings can also be given per slide `<section>` by setting the `data-timing` attribute (again, in seconds).


 ## Server Side Speaker Notes
@@ -1200,11 +1285,33 @@ Reveal.initialize({

 Then:

-1. Install [Node.js](http://nodejs.org/) (4.0.0 or later)
+1. Install [Node.js](http://nodejs.org/) (9.0.0 or later)
 2. Run `npm install`
 3. Run `node plugin/notes-server`


+## Plugins
+
+Plugins should register themselves with reveal.js by calling `Reveal.registerPlugin( 'myPluginID', MyPlugin )`. Registered plugin instances can optionally expose an "init" function that reveal.js will call to initialize them.
+
+When reveal.js is booted up via `Reveal.initialize()`, it will go through all registered plugins and invoke their "init" methods. If the "init" method returns a Promise, reveal.js will wait for that promise to be fulfilled before finishing the startup sequence and firing the [ready](#ready-event) event. Here's an example of a plugin that does some asynchronous work before reveal.js can proceed:
+
+```javascript
+let MyPlugin = {
+	init: () =>  new Promise( resolve => setTimeout( resolve, 3000 ) )
+};
+Reveal.registerPlugin( 'myPlugin', MyPlugin );
+Reveal.addEventListener( 'ready', () => console.log( 'Three seconds later...' ) );
+Reveal.initialize();
+```
+
+Note that reveal.js will *not* wait for init Promise fulfillment if the plugin is loaded as an [async dependency](#dependencies). If the plugin's init method does _not_ return a Promise, the plugin is considered ready right away and will not hold up the reveal.js startup sequence.
+
+### Retrieving Plugins
+
+If you want to check if a specific plugin is registered you can use the `Reveal.hasPlugin` method and pass in a plugin ID, for example: `Reveal.hasPlugin( 'myPlugin' )`. If you want to retrieve a plugin instance you can use `Reveal.getPlugin( 'myPlugin' )`.
+
+
 ## Multiplexing

 The multiplex plugin allows your audience to view the slides of the presentation you are controlling on their own phone, tablet or laptop. As the master presentation navigates the slides, all client presentations will update in real time. See a demo at [https://reveal-js-multiplex-ccjbegmaii.now.sh/](https://reveal-js-multiplex-ccjbegmaii.now.sh/).
@@ -1254,7 +1361,7 @@ Reveal.initialize({

 #### Client presentation

-Served from a publicly accessible static file server. Examples include: GitHub Pages, Amazon S3, Dreamhost, Akamai, etc. The more reliable, the better. Your audience can then access the client presentation via `http://example.com/path/to/presentation/client/index.html`, with the configuration below causing them to connect to the socket.io server as clients.
+Served from a publicly accessible static file server. Examples include: GitHub Pages, Amazon S3, Dreamhost, Akamai, etc. The more reliable, the better. Your audience can then access the client presentation via `https://example.com/path/to/presentation/client/index.html`, with the configuration below causing them to connect to the socket.io server as clients.

 Example configuration:

@@ -1288,7 +1395,7 @@ Server that receives the `slideChanged` events from the master presentation and

 Or you can use the socket.io server at [https://reveal-js-multiplex-ccjbegmaii.now.sh/](https://reveal-js-multiplex-ccjbegmaii.now.sh/).

-You'll need to generate a unique secret and token pair for your master and client presentations. To do so, visit `http://example.com/token`, where `http://example.com` is the location of your socket.io server. Or if you're going to use the socket.io server at [https://reveal-js-multiplex-ccjbegmaii.now.sh/](https://reveal-js-multiplex-ccjbegmaii.now.sh/), visit [https://reveal-js-multiplex-ccjbegmaii.now.sh/token](https://reveal-js-multiplex-ccjbegmaii.now.sh/token).
+You'll need to generate a unique secret and token pair for your master and client presentations. To do so, visit `https://example.com/token`, where `https://example.com` is the location of your socket.io server. Or if you're going to use the socket.io server at [https://reveal-js-multiplex-ccjbegmaii.now.sh/](https://reveal-js-multiplex-ccjbegmaii.now.sh/), visit [https://reveal-js-multiplex-ccjbegmaii.now.sh/token](https://reveal-js-multiplex-ccjbegmaii.now.sh/token).

 You are very welcome to point your presentations at the Socket.io server running at [https://reveal-js-multiplex-ccjbegmaii.now.sh/](https://reveal-js-multiplex-ccjbegmaii.now.sh/), but availability and stability are not guaranteed.

@@ -1351,7 +1458,7 @@ Reveal.initialize({

 If you want to display math equations in your presentation you can easily do so by including this plugin. The plugin is a very thin wrapper around the [MathJax](http://www.mathjax.org/) library. To use it you'll need to include it as a reveal.js dependency, [find our more about dependencies here](#dependencies).

-The plugin defaults to using [LaTeX](http://en.wikipedia.org/wiki/LaTeX) but that can be adjusted through the `math` configuration object. Note that MathJax is loaded from a remote server. If you want to use it offline you'll need to download a copy of the library and adjust the `mathjax` configuration value.
+The plugin defaults to using [LaTeX](https://en.wikipedia.org/wiki/LaTeX) but that can be adjusted through the `math` configuration object. Note that MathJax is loaded from a remote server. If you want to use it offline you'll need to download a copy of the library and adjust the `mathjax` configuration value.

 Below is an example of how the plugin can be configured. If you don't intend to change these values you do not need to include the `math` config object at all.

@@ -1361,9 +1468,9 @@ Reveal.initialize({

 	math: {
 		mathjax: 'https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.0/MathJax.js',
-		config: 'TeX-AMS_HTML-full'  // See http://docs.mathjax.org/en/latest/config-files.html
+		config: 'TeX-AMS_HTML-full', // See http://docs.mathjax.org/en/latest/config-files.html
 		// pass other options into `MathJax.Hub.Config()`
-		TeX: { Macros: macros }
+		TeX: { Macros: { RR: "{\\bf R}" } }
 	},

 	dependencies: [
@@ -1385,4 +1492,4 @@ If you want to include math inside of a presentation written in Markdown you nee

 MIT licensed

-Copyright (C) 2019 Hakim El Hattab, http://hakim.se
+Copyright (C) 2020 Hakim El Hattab, http://hakim.se
--- a/bower.json
+++ b/bower.json
@@ -1,6 +1,6 @@
 {
  "name": "reveal.js",
-  "version": "3.8.0",
+  "version": "3.9.2",
  "main": [
    "js/reveal.js",
    "css/reveal.css"
--- a/css/reveal.css
+++ b/css/reveal.css
@@ -3,7 +3,7 @@
 * http://revealjs.com
 * MIT licensed
 *
- * Copyright (C) 2019 Hakim El Hattab, http://hakim.se
+ * Copyright (C) 2020 Hakim El Hattab, http://hakim.se
 */
 /*********************************************
 * GLOBAL STYLES
@@ -77,29 +77,29 @@ body {
    text-decoration: line-through; }

 .reveal .slides section .fragment.fade-up {
-  -webkit-transform: translate(0, 20%);
-          transform: translate(0, 20%); }
+  -webkit-transform: translate(0, 40px);
+          transform: translate(0, 40px); }
  .reveal .slides section .fragment.fade-up.visible {
    -webkit-transform: translate(0, 0);
            transform: translate(0, 0); }

 .reveal .slides section .fragment.fade-down {
-  -webkit-transform: translate(0, -20%);
-          transform: translate(0, -20%); }
+  -webkit-transform: translate(0, -40px);
+          transform: translate(0, -40px); }
  .reveal .slides section .fragment.fade-down.visible {
    -webkit-transform: translate(0, 0);
            transform: translate(0, 0); }

 .reveal .slides section .fragment.fade-right {
-  -webkit-transform: translate(-20%, 0);
-          transform: translate(-20%, 0); }
+  -webkit-transform: translate(-40px, 0);
+          transform: translate(-40px, 0); }
  .reveal .slides section .fragment.fade-right.visible {
    -webkit-transform: translate(0, 0);
            transform: translate(0, 0); }

 .reveal .slides section .fragment.fade-left {
-  -webkit-transform: translate(20%, 0);
-          transform: translate(20%, 0); }
+  -webkit-transform: translate(40px, 0);
+          transform: translate(40px, 0); }
  .reveal .slides section .fragment.fade-left.visible {
    -webkit-transform: translate(0, 0);
            transform: translate(0, 0); }
@@ -227,7 +227,7 @@ body {
  bottom: 12px;
  right: 12px;
  left: auto;
-  z-index: 1;
+  z-index: 11;
  color: #000;
  pointer-events: none;
  font-size: 10px; }
@@ -312,7 +312,8 @@ body {
              transform: rotate(90deg); }
  .reveal .controls .navigate-down {
    right: 3.2em;
-    bottom: 0;
+    bottom: -1.4em;
+    padding-bottom: 1.4em;
    -webkit-transform: translateY(10px);
            transform: translateY(10px); }
    .reveal .controls .navigate-down .controls-arrow {
@@ -395,18 +396,18 @@ body {
    right: auto; }
  .reveal .controls[data-controls-layout="edges"] .navigate-left {
    top: 50%;
-    left: 8px;
+    left: 0.8em;
    margin-top: -1.8em; }
  .reveal .controls[data-controls-layout="edges"] .navigate-right {
    top: 50%;
-    right: 8px;
+    right: 0.8em;
    margin-top: -1.8em; }
  .reveal .controls[data-controls-layout="edges"] .navigate-up {
-    top: 8px;
+    top: 0.8em;
    left: 50%;
    margin-left: -1.8em; }
  .reveal .controls[data-controls-layout="edges"] .navigate-down {
-    bottom: 8px;
+    bottom: -0.3em;
    left: 50%;
    margin-left: -1.8em; } }

@@ -1453,9 +1454,16 @@ body {
  text-align: right;
  vertical-align: top; }

-.reveal .hljs[data-line-numbers]:not([data-line-numbers=""]) tr:not(.highlight-line) {
+.reveal .hljs.has-highlights tr:not(.highlight-line) {
  opacity: 0.4; }

+.reveal .hljs:not(:first-child).fragment {
+  position: absolute;
+  top: 0;
+  left: 0;
+  width: 100%;
+  box-sizing: border-box; }
+
 /*********************************************
 * ROLLING LINKS
 *********************************************/
--- a/css/reveal.scss
+++ b/css/reveal.scss
@@ -3,7 +3,7 @@
 * http://revealjs.com
 * MIT licensed
 *
- * Copyright (C) 2019 Hakim El Hattab, http://hakim.se
+ * Copyright (C) 2020 Hakim El Hattab, http://hakim.se
 */


@@ -102,7 +102,7 @@ body {
 }

 .reveal .slides section .fragment.fade-up {
-	transform: translate(0, 20%);
+	transform: translate(0, 40px);

 	&.visible {
 		transform: translate(0, 0);
@@ -110,7 +110,7 @@ body {
 }

 .reveal .slides section .fragment.fade-down {
-	transform: translate(0, -20%);
+	transform: translate(0, -40px);

 	&.visible {
 		transform: translate(0, 0);
@@ -118,7 +118,7 @@ body {
 }

 .reveal .slides section .fragment.fade-right {
-	transform: translate(-20%, 0);
+	transform: translate(-40px, 0);

 	&.visible {
 		transform: translate(0, 0);
@@ -126,7 +126,7 @@ body {
 }

 .reveal .slides section .fragment.fade-left {
-	transform: translate(20%, 0);
+	transform: translate(40px, 0);

 	&.visible {
 		transform: translate(0, 0);
@@ -263,7 +263,7 @@ $controlsArrowAngleActive: 36deg;
 	bottom: $spacing;
 	right: $spacing;
 	left: auto;
-	z-index: 1;
+	z-index: 11;
 	color: #000;
 	pointer-events: none;
 	font-size: 10px;
@@ -355,7 +355,8 @@ $controlsArrowAngleActive: 36deg;

 	.navigate-down {
 		right: $controlArrowSpacing + $controlArrowSize/2;
-		bottom: 0;
+		bottom: -$controlArrowSpacing;
+		padding-bottom: $controlArrowSpacing;
 		transform: translateY( 10px );

 		.controls-arrow {
@@ -452,7 +453,7 @@ $controlsArrowAngleActive: 36deg;
 // Edge aligned controls layout
@media screen and (min-width: 500px) {

-	$spacing: 8px;
+	$spacing: 0.8em;

 	.reveal .controls[data-controls-layout="edges"] {
 		& {
@@ -489,7 +490,7 @@ $controlsArrowAngleActive: 36deg;
 		}

 		.navigate-down {
-			bottom: $spacing;
+			bottom: $spacing - $controlArrowSpacing + 0.3em;
 			left: 50%;
 			margin-left: -$controlArrowSize/2;
 		}
@@ -1590,10 +1591,18 @@ $controlsArrowAngleActive: 36deg;
 	vertical-align: top;
 }

-.reveal .hljs[data-line-numbers]:not([data-line-numbers=""]) tr:not(.highlight-line) {
+.reveal .hljs.has-highlights tr:not(.highlight-line) {
 	opacity: 0.4;
 }

+.reveal .hljs:not(:first-child).fragment {
+	position: absolute;
+	top: 0;
+	left: 0;
+	width: 100%;
+	box-sizing: border-box;
+}
+

 /*********************************************
 * ROLLING LINKS
--- a/css/theme/README.md
+++ b/css/theme/README.md
@@ -4,7 +4,7 @@ Themes are written using Sass to keep things modular and reduce the need for rep

 ## Creating a Theme

-To create your own theme, start by duplicating a ```.scss``` file in [/css/theme/source](https://github.com/hakimel/reveal.js/blob/master/css/theme/source). It will be automatically compiled by Grunt from Sass to CSS (see the [Gruntfile](https://github.com/hakimel/reveal.js/blob/master/Gruntfile.js)) when you run `npm run build -- css-themes`.
+To create your own theme, start by duplicating a ```.scss``` file in [/css/theme/source](https://github.com/hakimel/reveal.js/blob/master/css/theme/source). It will be automatically compiled by Grunt from Sass to CSS (see the [Gruntfile](https://github.com/hakimel/reveal.js/blob/master/gruntfile.js)) when you run `npm run build -- css-themes`.

 Each theme file does four things in the following order:

--- a/demo.html
+++ b/demo.html
@@ -241,7 +241,7 @@

 				<section>
 					<h2>Pretty Code</h2>
-					<pre><code class="hljs" data-trim data-line-numbers="4,8-9">
+					<pre><code class="hljs" data-trim data-line-numbers="4|9|4,8-11">
 import React, { useState } from 'react';

 function Example() {
@@ -412,7 +412,7 @@ Reveal.addEventListener( 'customevent', function() {
 				dependencies: [
 					{ src: 'plugin/markdown/marked.js', condition: function() { return !!document.querySelector( '[data-markdown]' ); } },
 					{ src: 'plugin/markdown/markdown.js', condition: function() { return !!document.querySelector( '[data-markdown]' ); } },
-					{ src: 'plugin/highlight/highlight.js', async: true },
+					{ src: 'plugin/highlight/highlight.js' },
 					{ src: 'plugin/search/search.js', async: true },
 					{ src: 'plugin/zoom-js/zoom.js', async: true },
 					{ src: 'plugin/notes/notes.js', async: true }
--- a/gruntfile.js
+++ b/gruntfile.js
@@ -19,7 +19,7 @@ module.exports = grunt => {
 				' * http://revealjs.com\n' +
 				' * MIT licensed\n' +
 				' *\n' +
-				' * Copyright (C) 2019 Hakim El Hattab, http://hakim.se\n' +
+				' * Copyright (C) 2020 Hakim El Hattab, http://hakim.se\n' +
 				' */'
 		},

@@ -162,9 +162,6 @@ module.exports = grunt => {

 	});

-	grunt.loadNpmTasks('grunt-contrib-clean');
-	grunt.loadNpmTasks('grunt-contrib-nodeunit');
-
 	// Default task
 	grunt.registerTask( 'default', [ 'css', 'js' ] );

--- a/index.html
+++ b/index.html
@@ -37,11 +37,12 @@
 			// - https://github.com/hakimel/reveal.js#configuration
 			// - https://github.com/hakimel/reveal.js#dependencies
 			Reveal.initialize({
+				hash: true,
 				dependencies: [
 					{ src: 'plugin/markdown/marked.js' },
 					{ src: 'plugin/markdown/markdown.js' },
-					{ src: 'plugin/notes/notes.js', async: true },
-					{ src: 'plugin/highlight/highlight.js', async: true }
+					{ src: 'plugin/highlight/highlight.js' },
+					{ src: 'plugin/notes/notes.js', async: true }
 				]
 			});
 		</script>
--- a/js/reveal.js
+++ b/js/reveal.js
@@ -3,7 +3,7 @@
 * http://revealjs.com
 * MIT licensed
 *
- * Copyright (C) 2019 Hakim El Hattab, http://hakim.se
+ * Copyright (C) 2020 Hakim El Hattab, http://hakim.se
 */
 (function( root, factory ) {
 	if( typeof define === 'function' && define.amd ) {
@@ -26,14 +26,18 @@
 	var Reveal;

 	// The reveal.js version
-	var VERSION = '3.8.0';
+	var VERSION = '3.9.2';

 	var SLIDES_SELECTOR = '.slides section',
 		HORIZONTAL_SLIDES_SELECTOR = '.slides>section',
 		VERTICAL_SLIDES_SELECTOR = '.slides>section.present>section',
 		HOME_SLIDE_SELECTOR = '.slides>section:first-of-type',
+
 		UA = navigator.userAgent,

+		// Methods that may not be invoked via the postMessage API
+		POST_MESSAGE_METHOD_BLACKLIST = /registerPlugin|registerKeyboardShortcut|addKeyBinding|addEventListener/,
+
 		// Configuration defaults, can be overridden at initialization time
 		config = {

@@ -77,9 +81,9 @@
 			// - "c/t":	  Flattened slide number / total slides
 			//
 			// Alternatively, you can provide a function that returns the slide
-			// number for the current slide. The function needs to return an array
-			// with one string [slideNumber] or three strings [n1,delimiter,n2].
-			// See #formatSlideNumber().
+			// number for the current slide. The function should take in a slide
+			// object and return an array with one string [slideNumber] or
+			// three strings [n1,delimiter,n2]. See #formatSlideNumber().
 			slideNumber: false,

 			// Can be used to limit the contexts in which the slide number appears
@@ -270,6 +274,11 @@
 			// Number of slides away from the current that are visible
 			viewDistance: 3,

+			// Number of slides away from the current that are visible on mobile
+			// devices. It is advisable to set this to a lower number than
+			// viewDistance in order to save resources.
+			mobileViewDistance: 2,
+
 			// The display mode that will be used to show slides
 			display: 'block',

@@ -447,7 +456,8 @@
 	 */
 	function checkCapabilities() {

-		isMobileDevice = /(iphone|ipod|ipad|android)/gi.test( UA );
+		isMobileDevice = /(iphone|ipod|ipad|android)/gi.test( UA ) ||
+							( navigator.platform === 'MacIntel' && navigator.maxTouchPoints > 1 ); // iPadOS
 		isChrome = /chrome/i.test( UA ) && !/edge/i.test( UA );

 		var testElement = document.createElement( 'div' );
@@ -849,17 +859,10 @@
 		// Make sure stretch elements fit on slide
 		layoutSlideContents( slideWidth, slideHeight );

-		// Add each slide's index as attributes on itself, we need these
-		// indices to generate slide numbers below
-		toArray( dom.wrapper.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR ) ).forEach( function( hslide, h ) {
-			hslide.setAttribute( 'data-index-h', h );
-
-			if( hslide.classList.contains( 'stack' ) ) {
-				toArray( hslide.querySelectorAll( 'section' ) ).forEach( function( vslide, v ) {
-					vslide.setAttribute( 'data-index-h', h );
-					vslide.setAttribute( 'data-index-v', v );
-				} );
-			}
+		// Compute slide numbers now, before we start duplicating slides
+		var doingSlideNumbers = config.slideNumber && /all|print/i.test( config.showSlideNumber );
+		toArray( dom.wrapper.querySelectorAll( SLIDES_SELECTOR ) ).forEach( function( slide ) {
+			slide.setAttribute( 'data-slide-number', getSlideNumber( slide ) );
 		} );

 		// Slide and slide background layout
@@ -930,14 +933,11 @@
 				}

 				// Inject slide numbers if `slideNumbers` are enabled
-				if( config.slideNumber && /all|print/i.test( config.showSlideNumber ) ) {
-					var slideNumberH = parseInt( slide.getAttribute( 'data-index-h' ), 10 ) + 1,
-						slideNumberV = parseInt( slide.getAttribute( 'data-index-v' ), 10 ) + 1;
-
+				if( doingSlideNumbers ) {
 					var numberElement = document.createElement( 'div' );
 					numberElement.classList.add( 'slide-number' );
 					numberElement.classList.add( 'slide-number-pdf' );
-					numberElement.innerHTML = formatSlideNumber( slideNumberH, '.', slideNumberV );
+					numberElement.innerHTML = slide.getAttribute( 'data-slide-number' );
 					page.appendChild( numberElement );
 				}

@@ -1217,6 +1217,8 @@
 		if( data.backgroundColor ) element.style.backgroundColor = data.backgroundColor;
 		if( data.backgroundTransition ) element.setAttribute( 'data-background-transition', data.backgroundTransition );

+		if( slide.hasAttribute( 'data-preload' ) ) element.setAttribute( 'data-preload', '' );
+
 		// Background image options are set on the content wrapper
 		if( data.backgroundSize ) contentElement.style.backgroundSize = data.backgroundSize;
 		if( data.backgroundRepeat ) contentElement.style.backgroundRepeat = data.backgroundRepeat;
@@ -1276,7 +1278,20 @@

 					// Check if the requested method can be found
 					if( data.method && typeof Reveal[data.method] === 'function' ) {
-						Reveal[data.method].apply( Reveal, data.args );
+
+						if( POST_MESSAGE_METHOD_BLACKLIST.test( data.method ) === false ) {
+
+							var result = Reveal[data.method].apply( Reveal, data.args );
+
+							// Dispatch a postMessage event with the returned value from
+							// our method invocation for getter functions
+							dispatchPostMessage( 'callback', { method: data.method, result: result } );
+
+						}
+						else {
+							console.warn( 'reveal.js: "'+ data.method +'" is is blacklisted from the postMessage API' );
+						}
+
 					}
 				}
 			}, false );
@@ -1447,8 +1462,8 @@
 			keyboardShortcuts['&#8595;  ,  J'] = 'Navigate down';
 		}

-		keyboardShortcuts['Home  ,  &#8984;/CTRL &#8592;'] = 'First slide';
-		keyboardShortcuts['End  ,  &#8984;/CTRL &#8594;']  = 'Last slide';
+		keyboardShortcuts['Home  ,  Shift &#8592;']        = 'First slide';
+		keyboardShortcuts['End  ,  Shift &#8594;']         = 'Last slide';
 		keyboardShortcuts['B  ,  .']                       = 'Pause';
 		keyboardShortcuts['F']                             = 'Fullscreen';
 		keyboardShortcuts['ESC, O']                        = 'Slide overview';
@@ -1981,8 +1996,25 @@

 		// If we're in an iframe, post each reveal.js event to the
 		// parent window. Used by the notes plugin
+		dispatchPostMessage( type );
+
+	}
+
+	/**
+	 * Dispatched a postMessage of the given type from our window.
+	 */
+	function dispatchPostMessage( type, data ) {
+
 		if( config.postMessageEvents && window.parent !== window.self ) {
-			window.parent.postMessage( JSON.stringify({ namespace: 'reveal', eventName: type, state: getState() }), '*' );
+			var message = {
+				namespace: 'reveal',
+				eventName: type,
+				state: getState()
+			};
+
+			extend( message, data );
+
+			window.parent.postMessage( JSON.stringify( message ), '*' );
 		}

 	}
@@ -2243,10 +2275,12 @@
 					transformSlides( { layout: '' } );
 				}
 				else {
-					// Prefer zoom for scaling up so that content remains crisp.
-					// Don't use zoom to scale down since that can lead to shifts
-					// in text layout/line breaks.
-					if( scale > 1 && features.zoom ) {
+					// Zoom Scaling
+					// Content remains crisp no matter how much we scale. Side
+					// effects are minor differences in text layout and iframe
+					// viewports changing size. A 200x200 iframe viewport in a
+					// 2x zoomed presentation ends up having a 400x400 viewport.
+					if( scale > 1 && features.zoom && window.devicePixelRatio < 2 ) {
 						dom.slides.style.zoom = scale;
 						dom.slides.style.left = '';
 						dom.slides.style.top = '';
@@ -2254,7 +2288,10 @@
 						dom.slides.style.right = '';
 						transformSlides( { layout: '' } );
 					}
-					// Apply scale transform as a fallback
+					// Transform Scaling
+					// Content layout remains the exact same when scaled up.
+					// Side effect is content becoming blurred, especially with
+					// high scale values on ldpi screens.
 					else {
 						dom.slides.style.zoom = '';
 						dom.slides.style.left = '50%';
@@ -2623,34 +2660,37 @@
 	}

 	/**
-	 * Return a hash URL that will resolve to the current slide location.
+	 * Return a hash URL that will resolve to the given slide location.
+	 *
+	 * @param {HTMLElement} [slide=currentSlide] The slide to link to
 	 */
-	function locationHash() {
+	function locationHash( slide ) {

 		var url = '/';

 		// Attempt to create a named link based on the slide's ID
-		var id = currentSlide ? currentSlide.getAttribute( 'id' ) : null;
+		var s = slide || currentSlide;
+		var id = s ? s.getAttribute( 'id' ) : null;
 		if( id ) {
 			id = encodeURIComponent( id );
 		}

-		var indexf;
-		if( config.fragmentInURL ) {
-			indexf = getIndices().f;
+		var index = getIndices( slide );
+		if( !config.fragmentInURL ) {
+			index.f = undefined;
 		}

 		// If the current slide has an ID, use that as a named link,
 		// but we don't support named links with a fragment index
-		if( typeof id === 'string' && id.length && indexf === undefined ) {
+		if( typeof id === 'string' && id.length && index.f === undefined ) {
 			url = '/' + id;
 		}
 		// Otherwise use the /h/v index
 		else {
 			var hashIndexBase = config.hashOneBasedIndex ? 1 : 0;
-			if( indexh > 0 || indexv > 0 || indexf !== undefined ) url += indexh + hashIndexBase;
-			if( indexv > 0 || indexf !== undefined ) url += '/' + (indexv + hashIndexBase );
-			if( indexf !== undefined ) url += '/' + indexf;
+			if( index.h > 0 || index.v > 0 || index.f !== undefined ) url += index.h + hashIndexBase;
+			if( index.v > 0 || index.f !== undefined ) url += '/' + (index.v + hashIndexBase );
+			if( index.f !== undefined ) url += '/' + index.f;
 		}

 		return url;
@@ -3039,11 +3079,11 @@
 		syncBackground( slide );
 		syncFragments( slide );

+		loadSlide( slide );
+
 		updateBackground();
 		updateNotes();

-		loadSlide( slide );
-
 	}

 	/**
@@ -3255,9 +3295,10 @@
 			// be visible
 			var viewDistance = isOverview() ? 10 : config.viewDistance;

-			// Limit view distance on weaker devices
+			// Shorten the view distance on devices that typically have
+			// less resources
 			if( isMobileDevice ) {
-				viewDistance = isOverview() ? 6 : 2;
+				viewDistance = isOverview() ? 6 : config.mobileViewDistance;
 			}

 			// All slides need to be visible when exporting to PDF
@@ -3309,7 +3350,7 @@
 			}

 			// Flag if there are ANY vertical slides, anywhere in the deck
-			if( dom.wrapper.querySelectorAll( '.slides>section>section' ).length ) {
+			if( hasVerticalSlides() ) {
 				dom.wrapper.classList.add( 'has-vertical-slides' );
 			}
 			else {
@@ -3317,7 +3358,7 @@
 			}

 			// Flag if there are ANY horizontal slides, anywhere in the deck
-			if( dom.wrapper.querySelectorAll( '.slides>section' ).length > 1 ) {
+			if( hasHorizontalSlides() ) {
 				dom.wrapper.classList.add( 'has-horizontal-slides' );
 			}
 			else {
@@ -3393,48 +3434,58 @@

 		// Update slide number if enabled
 		if( config.slideNumber && dom.slideNumber ) {
-
-			var value;
-			var format = 'h.v';
-
-			if( typeof config.slideNumber === 'function' ) {
-				value = config.slideNumber();
-			}
-			else {
-				// Check if a custom number format is available
-				if( typeof config.slideNumber === 'string' ) {
-					format = config.slideNumber;
-				}
-
-				// If there are ONLY vertical slides in this deck, always use
-				// a flattened slide number
-				if( !/c/.test( format ) && dom.wrapper.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR ).length === 1 ) {
-					format = 'c';
-				}
-
-				value = [];
-				switch( format ) {
-					case 'c':
-						value.push( getSlidePastCount() + 1 );
-						break;
-					case 'c/t':
-						value.push( getSlidePastCount() + 1, '/', getTotalSlides() );
-						break;
-					case 'h/v':
-						value.push( indexh + 1 );
-						if( isVerticalSlide() ) value.push( '/', indexv + 1 );
-						break;
-					default:
-						value.push( indexh + 1 );
-						if( isVerticalSlide() ) value.push( '.', indexv + 1 );
-				}
-			}
-
-			dom.slideNumber.innerHTML = formatSlideNumber( value[0], value[1], value[2] );
+			dom.slideNumber.innerHTML = getSlideNumber();
 		}

 	}

+	/**
+	 * Returns the HTML string corresponding to the current slide number,
+	 * including formatting.
+	 */
+	function getSlideNumber( slide ) {
+
+		var value;
+		var format = 'h.v';
+		if( slide === undefined ) {
+			slide = currentSlide;
+		}
+
+		if ( typeof config.slideNumber === 'function' ) {
+			value = config.slideNumber( slide );
+		} else {
+			// Check if a custom number format is available
+			if( typeof config.slideNumber === 'string' ) {
+				format = config.slideNumber;
+			}
+
+			// If there are ONLY vertical slides in this deck, always use
+			// a flattened slide number
+			if( !/c/.test( format ) && dom.wrapper.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR ).length === 1 ) {
+				format = 'c';
+			}
+
+			value = [];
+			switch( format ) {
+				case 'c':
+					value.push( getSlidePastCount( slide ) + 1 );
+					break;
+				case 'c/t':
+					value.push( getSlidePastCount( slide ) + 1, '/', getTotalSlides() );
+					break;
+				default:
+					var indices = getIndices( slide );
+					value.push( indices.h + 1 );
+					var sep = format === 'h/v' ? '/' : '.';
+					if( isVerticalSlide( slide ) ) value.push( sep, indices.v + 1 );
+			}
+		}
+
+		var url = '#' + locationHash( slide );
+		return formatSlideNumber( value[0], value[1], value[2], url );
+
+	}
+
 	/**
 	 * Applies HTML formatting to a slide number before it's
 	 * written to the DOM.
@@ -3442,11 +3493,14 @@
 	 * @param {number} a Current slide
 	 * @param {string} delimiter Character to separate slide numbers
 	 * @param {(number|*)} b Total slides
+	 * @param {HTMLElement} [url='#'+locationHash()] The url to link to
 	 * @return {string} HTML string fragment
 	 */
-	function formatSlideNumber( a, delimiter, b ) {
+	function formatSlideNumber( a, delimiter, b, url ) {

-		var url = '#' + locationHash();
+		if( url === undefined ) {
+			url = '#' + locationHash();
+		}
 		if( typeof b === 'number' && !isNaN( b ) ) {
 			return  '<a href="' + url + '">' +
 					'<span class="slide-number-a">'+ a +'</span>' +
@@ -3599,7 +3653,7 @@
 		// Stop content inside of previous backgrounds
 		if( previousBackground ) {

-			stopEmbeddedContent( previousBackground );
+			stopEmbeddedContent( previousBackground, { unloadIframes: !shouldPreload( previousBackground ) } );

 		}

@@ -3778,6 +3832,7 @@
 			background.style.display = 'block';

 			var backgroundContent = slide.slideBackgroundContentElement;
+			var backgroundIframe = slide.getAttribute( 'data-background-iframe' );

 			// If the background contains media, load it
 			if( background.hasAttribute( 'data-loaded' ) === false ) {
@@ -3786,8 +3841,7 @@
 				var backgroundImage = slide.getAttribute( 'data-background-image' ),
 					backgroundVideo = slide.getAttribute( 'data-background-video' ),
 					backgroundVideoLoop = slide.hasAttribute( 'data-background-video-loop' ),
-					backgroundVideoMuted = slide.hasAttribute( 'data-background-video-muted' ),
-					backgroundIframe = slide.getAttribute( 'data-background-iframe' );
+					backgroundVideoMuted = slide.hasAttribute( 'data-background-video-muted' );

 				// Images
 				if( backgroundImage ) {
@@ -3827,15 +3881,9 @@
 					iframe.setAttribute( 'allowfullscreen', '' );
 					iframe.setAttribute( 'mozallowfullscreen', '' );
 					iframe.setAttribute( 'webkitallowfullscreen', '' );
+					iframe.setAttribute( 'allow', 'autoplay' );

-					// Only load autoplaying content when the slide is shown to
-					// avoid having it play in the background
-					if( /autoplay=(1|true|yes)/gi.test( backgroundIframe ) ) {
-						iframe.setAttribute( 'data-src', backgroundIframe );
-					}
-					else {
-						iframe.setAttribute( 'src', backgroundIframe );
-					}
+					iframe.setAttribute( 'data-src', backgroundIframe );

 					iframe.style.width  = '100%';
 					iframe.style.height = '100%';
@@ -3846,6 +3894,19 @@
 				}
 			}

+			// Start loading preloadable iframes
+			var backgroundIframeElement = backgroundContent.querySelector( 'iframe[data-src]' );
+			if( backgroundIframeElement ) {
+
+				// Check if this iframe is eligible to be preloaded
+				if( shouldPreload( background ) && !/autoplay=(1|true|yes)/gi.test( backgroundIframe ) ) {
+					if( backgroundIframeElement.getAttribute( 'src' ) !== backgroundIframe ) {
+						backgroundIframeElement.setAttribute( 'src', backgroundIframe );
+					}
+				}
+
+			}
+
 		}

 	}
@@ -3865,6 +3926,11 @@
 		var background = getSlideBackground( slide );
 		if( background ) {
 			background.style.display = 'none';
+
+			// Unload any background iframes
+			toArray( background.querySelectorAll( 'iframe[src]' ) ).forEach( function( element ) {
+				element.removeAttribute( 'src' );
+			} );
 		}

 		// Reset lazy-loaded media elements with src attributes
@@ -4185,9 +4251,15 @@
 	 * Returns the number of past slides. This can be used as a global
 	 * flattened index for slides.
 	 *
+	 * @param {HTMLElement} [slide=currentSlide] The slide we're counting before
+	 *
 	 * @return {number} Past slide count
 	 */
-	function getSlidePastCount() {
+	function getSlidePastCount( slide ) {
+
+		if( slide === undefined ) {
+			slide = currentSlide;
+		}

 		var horizontalSlides = toArray( dom.wrapper.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR ) );

@@ -4203,7 +4275,7 @@
 			for( var j = 0; j < verticalSlides.length; j++ ) {

 				// Stop as soon as we arrive at the present
-				if( verticalSlides[j].classList.contains( 'present' ) ) {
+				if( verticalSlides[j] === slide ) {
 					break mainLoop;
 				}

@@ -4212,7 +4284,7 @@
 			}

 			// Stop as soon as we arrive at the present
-			if( horizontalSlide.classList.contains( 'present' ) ) {
+			if( horizontalSlide === slide ) {
 				break;
 			}

@@ -4429,7 +4501,44 @@
 	 */
 	function getSlides() {

-		return toArray( dom.wrapper.querySelectorAll( SLIDES_SELECTOR + ':not(.stack)' ));
+		return toArray( dom.wrapper.querySelectorAll( SLIDES_SELECTOR + ':not(.stack)' ) );
+
+	}
+
+	/**
+	 * Returns a list of all horizontal slides in the deck. Each
+	 * vertical stack is included as one horizontal slide in the
+	 * resulting array.
+	 */
+	function getHorizontalSlides() {
+
+		return toArray( dom.wrapper.querySelectorAll( HORIZONTAL_SLIDES_SELECTOR ) );
+
+	}
+
+	/**
+	 * Returns all vertical slides that exist within this deck.
+	 */
+	function getVerticalSlides() {
+
+		return toArray( dom.wrapper.querySelectorAll( '.slides>section>section' ) );
+
+	}
+
+	/**
+	 * Returns true if there are at least two horizontal slides.
+	 */
+	function hasHorizontalSlides() {
+
+		return getHorizontalSlides().length > 1;
+	}
+
+	/**
+	 * Returns true if there are at least two vertical slides.
+	 */
+	function hasVerticalSlides() {
+
+		return getVerticalSlides().length > 1;

 	}

@@ -4667,6 +4776,8 @@

 			if( fragments.length ) {

+				var maxIndex = 0;
+
 				if( typeof index !== 'number' ) {
 					var currentFragment = sortFragments( currentSlide.querySelectorAll( '.fragment.visible' ) ).pop();
 					if( currentFragment ) {
@@ -4680,6 +4791,8 @@
 						i = parseInt( el.getAttribute( 'data-fragment-index' ), 10 );
 					}

+					maxIndex = Math.max( maxIndex, i );
+
 					// Visible fragments
 					if( i <= index ) {
 						if( !el.classList.contains( 'visible' ) ) changedFragments.shown.push( el );
@@ -4703,6 +4816,13 @@

 				} );

+				// Write the current fragment index to the slide <section>.
+				// This can be used by end users to apply styles based on
+				// the current fragment index.
+				index = typeof index === 'number' ? index : -1;
+				index = Math.max( Math.min( index, maxIndex ), -1 );
+				currentSlide.setAttribute( 'data-fragment', index );
+
 			}

 		}
@@ -5116,8 +5236,8 @@

 		// Whitelist specific modified + keycode combinations
 		var prevSlideShortcut = event.shiftKey && event.keyCode === 32;
-		var firstSlideShortcut = ( event.metaKey || event.ctrlKey ) && keyCode === 37;
-		var lastSlideShortcut = ( event.metaKey || event.ctrlKey ) && keyCode === 39;
+		var firstSlideShortcut = event.shiftKey && keyCode === 37;
+		var lastSlideShortcut = event.shiftKey && keyCode === 39;

 		// Prevent all other events when a modifier is pressed
 		var unusedModifier = 	!prevSlideShortcut && !firstSlideShortcut && !lastSlideShortcut &&
@@ -5144,6 +5264,10 @@
 			return false;
 		}

+		// Use linear navigation if we're configured to OR if
+		// the presentation is one-dimensional
+		var useLinearMode = config.navigationMode === 'linear' || !hasHorizontalSlides() || !hasVerticalSlides();
+
 		var triggered = false;

 		// 1. User defined key bindings
@@ -5216,7 +5340,7 @@
 				if( firstSlideShortcut ) {
 					slide( 0 );
 				}
-				else if( !isOverview() && config.navigationMode === 'linear' ) {
+				else if( !isOverview() && useLinearMode ) {
 					navigatePrev();
 				}
 				else {
@@ -5228,7 +5352,7 @@
 				if( lastSlideShortcut ) {
 					slide( Number.MAX_VALUE );
 				}
-				else if( !isOverview() && config.navigationMode === 'linear' ) {
+				else if( !isOverview() && useLinearMode ) {
 					navigateNext();
 				}
 				else {
@@ -5237,7 +5361,7 @@
 			}
 			// K, UP
 			else if( keyCode === 75 || keyCode === 38 ) {
-				if( !isOverview() && config.navigationMode === 'linear' ) {
+				if( !isOverview() && useLinearMode ) {
 					navigatePrev();
 				}
 				else {
@@ -5246,7 +5370,7 @@
 			}
 			// J, DOWN
 			else if( keyCode === 74 || keyCode === 40 ) {
-				if( !isOverview() && config.navigationMode === 'linear' ) {
+				if( !isOverview() && useLinearMode ) {
 					navigateNext();
 				}
 				else {
@@ -5356,19 +5480,49 @@

 				if( deltaX > touch.threshold && Math.abs( deltaX ) > Math.abs( deltaY ) ) {
 					touch.captured = true;
-					navigateLeft();
+					if( config.navigationMode === 'linear' ) {
+						if( config.rtl ) {
+							navigateNext();
+						}
+						else {
+							navigatePrev();
+						}
+					}
+					else {
+						navigateLeft();
+					}
 				}
 				else if( deltaX < -touch.threshold && Math.abs( deltaX ) > Math.abs( deltaY ) ) {
 					touch.captured = true;
-					navigateRight();
+					if( config.navigationMode === 'linear' ) {
+						if( config.rtl ) {
+							navigatePrev();
+						}
+						else {
+							navigateNext();
+						}
+					}
+					else {
+						navigateRight();
+					}
 				}
 				else if( deltaY > touch.threshold ) {
 					touch.captured = true;
-					navigateUp();
+					if( config.navigationMode === 'linear' ) {
+						navigatePrev();
+					}
+					else {
+						navigateUp();
+					}
 				}
 				else if( deltaY < -touch.threshold ) {
 					touch.captured = true;
-					navigateDown();
+					if( config.navigationMode === 'linear' ) {
+						navigateNext();
+					}
+					else {
+						navigateDown();
+					}
 				}

 				// If we're embedded, only block touch events if they have
@@ -5905,6 +6059,15 @@
 		// Returns the speaker notes string for a slide, or null
 		getSlideNotes: getSlideNotes,

+		// Returns an array with all horizontal/vertical slides in the deck
+		getHorizontalSlides: getHorizontalSlides,
+		getVerticalSlides: getVerticalSlides,
+
+		// Checks if the presentation contains two or more
+		// horizontal/vertical slides
+		hasHorizontalSlides: hasHorizontalSlides,
+		hasVerticalSlides: hasVerticalSlides,
+
 		// Returns the previous slide element, may be null
 		getPreviousSlide: function() {
 			return previousSlide;
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,6 +1,6 @@
 {
  "name": "reveal.js",
-  "version": "3.8.0",
+  "version": "3.9.2",
  "lockfileVersion": 1,
  "requires": true,
  "dependencies": {
@@ -44,21 +44,21 @@
      "dev": true
    },
    "agent-base": {
-      "version": "4.2.1",
-      "resolved": "https://registry.npmjs.org/agent-base/-/agent-base-4.2.1.tgz",
-      "integrity": "sha512-JVwXMr9nHYTUXsBFKUqhJwvlcYU/blreOEUkhNR2eXZIvwd+c+o5V4MgDPKWnMS/56awN3TRzIP+KoPn+roQtg==",
+      "version": "4.3.0",
+      "resolved": "https://registry.npmjs.org/agent-base/-/agent-base-4.3.0.tgz",
+      "integrity": "sha512-salcGninV0nPrwpGNn4VTXBb1SOuXQBiqbrNXoeizJsHrsL6ERFM2Ne3JUSBWRE6aeNJI2ROP/WEEIDUiDe3cg==",
      "dev": true,
      "requires": {
        "es6-promisify": "^5.0.0"
      }
    },
    "ajv": {
-      "version": "6.9.2",
-      "resolved": "https://registry.npmjs.org/ajv/-/ajv-6.9.2.tgz",
-      "integrity": "sha512-4UFy0/LgDo7Oa/+wOAlj44tp9K78u38E5/359eSrqEp1Z5PdVfimCcs7SluXMP755RUQu6d2b4AvF0R1C9RZjg==",
+      "version": "6.11.0",
+      "resolved": "https://registry.npmjs.org/ajv/-/ajv-6.11.0.tgz",
+      "integrity": "sha512-nCprB/0syFYy9fVYU1ox1l2KN8S9I+tziH8D4zdZuLT3N6RMlGSGt5FSTpAiHB/Whv8Qs1cWHma1aMKZyaHRKA==",
      "dev": true,
      "requires": {
-        "fast-deep-equal": "^2.0.1",
+        "fast-deep-equal": "^3.1.1",
        "fast-json-stable-stringify": "^2.0.0",
        "json-schema-traverse": "^0.4.1",
        "uri-js": "^4.2.2"
@@ -275,9 +275,9 @@
      "dev": true
    },
    "aws4": {
-      "version": "1.8.0",
-      "resolved": "https://registry.npmjs.org/aws4/-/aws4-1.8.0.tgz",
-      "integrity": "sha512-ReZxvNHIOv88FlT7rxcXIIC0fPt4KZqZbOlivyWtXLt8ESx84zd3kMC6iK5jVeS2qt+g7ftS7ye4fi06X5rtRQ==",
+      "version": "1.9.1",
+      "resolved": "https://registry.npmjs.org/aws4/-/aws4-1.9.1.tgz",
+      "integrity": "sha512-wMHVg2EOHaMRxbzgFJ9gtjOOCrI80OHLG14rxi28XwOW8ux6IiEbRCGGGqCtdAIg4FQCbW20k9RsT4y3gJlFug==",
      "dev": true
    },
    "backo2": {
@@ -712,9 +712,9 @@
      "dev": true
    },
    "combined-stream": {
-      "version": "1.0.7",
-      "resolved": "https://registry.npmjs.org/combined-stream/-/combined-stream-1.0.7.tgz",
-      "integrity": "sha512-brWl9y6vOB1xYPZcpZde3N9zDByXTosAeMDo4p1wzo6UMOX4vumB+TP1RZ76sfE6Md68Q0NJSrE/gbezd4Ul+w==",
+      "version": "1.0.8",
+      "resolved": "https://registry.npmjs.org/combined-stream/-/combined-stream-1.0.8.tgz",
+      "integrity": "sha512-FQN4MRfuJeHf7cBbBMJFXhKSDq+2kAArBlmRBvcvFE5BB1HZKXtSFASDhdlz9zOYwxh8lDdnvmMOe/+5cdoEdg==",
      "dev": true,
      "requires": {
        "delayed-stream": "~1.0.0"
@@ -1263,9 +1263,9 @@
      }
    },
    "es6-promise": {
-      "version": "4.2.6",
-      "resolved": "https://registry.npmjs.org/es6-promise/-/es6-promise-4.2.6.tgz",
-      "integrity": "sha512-aRVgGdnmW2OiySVPUC9e6m+plolMAJKjZnQlCwNSuK5yQ0JN61DZSO1X1Ufd1foqWRAlig0rhduTCHe7sVtK5Q==",
+      "version": "4.2.8",
+      "resolved": "https://registry.npmjs.org/es6-promise/-/es6-promise-4.2.8.tgz",
+      "integrity": "sha512-HJDGx5daxeIvxdBxvG2cb9g4tEvwIk3i8+nhX0yGrYmZUzbkdg8QbDevheDB8gd0//uPj4c1EQua8Q+MViT0/w==",
      "dev": true
    },
    "es6-promisify": {
@@ -1615,9 +1615,9 @@
      }
    },
    "extend": {
-      "version": "3.0.0",
-      "resolved": "https://registry.npmjs.org/extend/-/extend-3.0.0.tgz",
-      "integrity": "sha1-WkdDU7nzNT3dgXbf03uRyDpG8dQ=",
+      "version": "3.0.2",
+      "resolved": "https://registry.npmjs.org/extend/-/extend-3.0.2.tgz",
+      "integrity": "sha512-fjquC59cD7CyW6urNXK0FBufkZcoiGG80wTuPujX590cB5Ttln20E2UB4S/WARVqhXffZl2LNgS+gQdPIIim/g==",
      "dev": true
    },
    "extend-shallow": {
@@ -1737,15 +1737,15 @@
          "dev": true
        },
        "process-nextick-args": {
-          "version": "2.0.0",
-          "resolved": "https://registry.npmjs.org/process-nextick-args/-/process-nextick-args-2.0.0.tgz",
-          "integrity": "sha512-MtEC1TqN0EU5nephaJ4rAtThHtC86dNN9qCuEhtshvpVBkAW5ZO7BASN9REnF9eoXGcRub+pFuKEpOHE+HbEMw==",
+          "version": "2.0.1",
+          "resolved": "https://registry.npmjs.org/process-nextick-args/-/process-nextick-args-2.0.1.tgz",
+          "integrity": "sha512-3ouUOpQhtgrbOa17J7+uxOTpITYWaGP7/AhoR3+A+/1e9skrzelGi/dXzEYyvbxubEF6Wn2ypscTKiKJFFn1ag==",
          "dev": true
        },
        "readable-stream": {
-          "version": "2.3.6",
-          "resolved": "http://registry.npmjs.org/readable-stream/-/readable-stream-2.3.6.tgz",
-          "integrity": "sha512-tQtKA9WIAhBF3+VLAseyMqZeBjW0AHJoxOtYqSUZNJxauErmLbVm2FW1y+J/YA9dUrAC39ITejlZWhVIwawkKw==",
+          "version": "2.3.7",
+          "resolved": "https://registry.npmjs.org/readable-stream/-/readable-stream-2.3.7.tgz",
+          "integrity": "sha512-Ebho8K4jIbHAxnuxi7o42OrZgF/ZTNcsZj6nRKyUmkhLFq8CHItp/fy6hQZuZmP/n3yZ9VBUbp4zz/mX8hmYPw==",
          "dev": true,
          "requires": {
            "core-util-is": "~1.0.0",
@@ -1775,15 +1775,15 @@
      "dev": true
    },
    "fast-deep-equal": {
-      "version": "2.0.1",
-      "resolved": "https://registry.npmjs.org/fast-deep-equal/-/fast-deep-equal-2.0.1.tgz",
-      "integrity": "sha1-ewUhjd+WZ79/Nwv3/bLLFf3Qqkk=",
+      "version": "3.1.1",
+      "resolved": "https://registry.npmjs.org/fast-deep-equal/-/fast-deep-equal-3.1.1.tgz",
+      "integrity": "sha512-8UEa58QDLauDNfpbrX55Q9jrGHThw2ZMdOky5Gl1CDtVeJDPVrG4Jxx1N8jw2gkWaff5UUuX1KJd+9zGe2B+ZA==",
      "dev": true
    },
    "fast-json-stable-stringify": {
-      "version": "2.0.0",
-      "resolved": "https://registry.npmjs.org/fast-json-stable-stringify/-/fast-json-stable-stringify-2.0.0.tgz",
-      "integrity": "sha1-1RQsDK7msRifh9OnYREGT4bIu/I=",
+      "version": "2.1.0",
+      "resolved": "https://registry.npmjs.org/fast-json-stable-stringify/-/fast-json-stable-stringify-2.1.0.tgz",
+      "integrity": "sha512-lhd/wF+Lk98HZoTCtlVraHtfh5XYijIjalXck7saUtuanSDyLMxnHhSXEDJqHxD7msR8D0uCmqlkwjCV8xvwHw==",
      "dev": true
    },
    "faye-websocket": {
@@ -1988,9 +1988,9 @@
      "dev": true
    },
    "fstream": {
-      "version": "1.0.11",
-      "resolved": "https://registry.npmjs.org/fstream/-/fstream-1.0.11.tgz",
-      "integrity": "sha1-XB+x8RdHcRTwYyoOtLcbPLD9MXE=",
+      "version": "1.0.12",
+      "resolved": "https://registry.npmjs.org/fstream/-/fstream-1.0.12.tgz",
+      "integrity": "sha512-WvJ193OHa0GHPEL+AycEJgxvBEwyfRkN1vhjca23OaPVMCaLCXTd5qAu82AjTcgP1UJmytkOKb63Ypde7raDIg==",
      "dev": true,
      "requires": {
        "graceful-fs": "^4.1.2",
@@ -2305,9 +2305,9 @@
          }
        },
        "lodash": {
-          "version": "4.17.11",
-          "resolved": "https://registry.npmjs.org/lodash/-/lodash-4.17.11.tgz",
-          "integrity": "sha512-cQKh8igo5QUhZ7lg38DYWAxMvjSAKG0A8wGSVimP07SIUEK2UO+arSRKbRZWtelMtN5V0Hkwh5ryOto/SshYIg==",
+          "version": "4.17.15",
+          "resolved": "https://registry.npmjs.org/lodash/-/lodash-4.17.15.tgz",
+          "integrity": "sha512-8xOcRHvCjnocdS5cpwXQXVzmmh5e5+saE2QGoeQmbKmRS6J3VQppPOIt0MnmE+4xlZoumy0GPG0D0MVIQbNA1A==",
          "dev": true
        }
      }
@@ -2790,12 +2790,12 @@
      "dev": true
    },
    "https-proxy-agent": {
-      "version": "2.2.1",
-      "resolved": "https://registry.npmjs.org/https-proxy-agent/-/https-proxy-agent-2.2.1.tgz",
-      "integrity": "sha512-HPCTS1LW51bcyMYbxUIOO4HEOlQ1/1qRaFWcyxvwaqUS9TY88aoEuHUY33kuAh1YhVVaDQhLZsnPd+XNARWZlQ==",
+      "version": "2.2.4",
+      "resolved": "https://registry.npmjs.org/https-proxy-agent/-/https-proxy-agent-2.2.4.tgz",
+      "integrity": "sha512-OmvfoQ53WLjtA9HeYP9RNrWMJzzAz1JGaSFr1nijg0PVR1JaD/xbJq1mdEIIlxGpXp9eSe/O2LgU9DJmTPd0Eg==",
      "dev": true,
      "requires": {
-        "agent-base": "^4.1.0",
+        "agent-base": "^4.3.0",
        "debug": "^3.1.0"
      },
      "dependencies": {
@@ -3120,9 +3120,9 @@
      "dev": true
    },
    "js-yaml": {
-      "version": "3.13.0",
-      "resolved": "https://registry.npmjs.org/js-yaml/-/js-yaml-3.13.0.tgz",
-      "integrity": "sha512-pZZoSxcCYco+DIKBTimr67J6Hy+EYGZDY/HCWC+iAEA9h1ByhMXAIVUXMcMFpOCxQ/xjXmPI2MkDL5HRm5eFrQ==",
+      "version": "3.13.1",
+      "resolved": "https://registry.npmjs.org/js-yaml/-/js-yaml-3.13.1.tgz",
+      "integrity": "sha512-YfbcO7jXDdyj0DGxYVSlSeQNHbD7XPWvrVWeVUujrQEoZzWJIRrCPoyk6kL6IAjAG2IolMK4T0hNUe0HOUs5Jw==",
      "dev": true,
      "requires": {
        "argparse": "^1.0.7",
@@ -3276,21 +3276,9 @@
      }
    },
    "lodash": {
-      "version": "4.17.11",
-      "resolved": "https://registry.npmjs.org/lodash/-/lodash-4.17.11.tgz",
-      "integrity": "sha512-cQKh8igo5QUhZ7lg38DYWAxMvjSAKG0A8wGSVimP07SIUEK2UO+arSRKbRZWtelMtN5V0Hkwh5ryOto/SshYIg==",
-      "dev": true
-    },
-    "lodash.assign": {
-      "version": "4.2.0",
-      "resolved": "https://registry.npmjs.org/lodash.assign/-/lodash.assign-4.2.0.tgz",
-      "integrity": "sha1-DZnzzNem0mHRm9rrkkUAXShYCOc=",
-      "dev": true
-    },
-    "lodash.clonedeep": {
-      "version": "4.5.0",
-      "resolved": "https://registry.npmjs.org/lodash.clonedeep/-/lodash.clonedeep-4.5.0.tgz",
-      "integrity": "sha1-4j8/nE+Pvd6HJSnBBxhXoIblzO8=",
+      "version": "4.17.15",
+      "resolved": "https://registry.npmjs.org/lodash/-/lodash-4.17.15.tgz",
+      "integrity": "sha512-8xOcRHvCjnocdS5cpwXQXVzmmh5e5+saE2QGoeQmbKmRS6J3VQppPOIt0MnmE+4xlZoumy0GPG0D0MVIQbNA1A==",
      "dev": true
    },
    "lodash.isfinite": {
@@ -3299,12 +3287,6 @@
      "integrity": "sha1-+4m2WpqAKBgz8LdHizpRBPiY67M=",
      "dev": true
    },
-    "lodash.mergewith": {
-      "version": "4.6.1",
-      "resolved": "https://registry.npmjs.org/lodash.mergewith/-/lodash.mergewith-4.6.1.tgz",
-      "integrity": "sha512-eWw5r+PYICtEBgrBE5hhlT6aAa75f411bgDz/ZL2KZqYV03USvucsxcHUIlGTDTECs1eunpI7HOV7U+WLDvNdQ==",
-      "dev": true
-    },
    "loud-rejection": {
      "version": "1.6.0",
      "resolved": "https://registry.npmjs.org/loud-rejection/-/loud-rejection-1.6.0.tgz",
@@ -3431,18 +3413,18 @@
      "dev": true
    },
    "mime-db": {
-      "version": "1.38.0",
-      "resolved": "https://registry.npmjs.org/mime-db/-/mime-db-1.38.0.tgz",
-      "integrity": "sha512-bqVioMFFzc2awcdJZIzR3HjZFX20QhilVS7hytkKrv7xFAn8bM1gzc/FOX2awLISvWe0PV8ptFKcon+wZ5qYkg==",
+      "version": "1.43.0",
+      "resolved": "https://registry.npmjs.org/mime-db/-/mime-db-1.43.0.tgz",
+      "integrity": "sha512-+5dsGEEovYbT8UY9yD7eE4XTc4UwJ1jBYlgaQQF38ENsKR3wj/8q8RFZrF9WIZpB2V1ArTVFUva8sAul1NzRzQ==",
      "dev": true
    },
    "mime-types": {
-      "version": "2.1.22",
-      "resolved": "https://registry.npmjs.org/mime-types/-/mime-types-2.1.22.tgz",
-      "integrity": "sha512-aGl6TZGnhm/li6F7yx82bJiBZwgiEa4Hf6CNr8YO+r5UHr53tSTYZb102zyU50DOWWKeOv0uQLRL0/9EiKWCog==",
+      "version": "2.1.26",
+      "resolved": "https://registry.npmjs.org/mime-types/-/mime-types-2.1.26.tgz",
+      "integrity": "sha512-01paPWYgLrkqAyrlDorC1uDwl2p3qZT7yl806vW7DvDoxwXi46jsjFbg+WdwotBIk6/MbEhO/dh5aZ5sNj/dWQ==",
      "dev": true,
      "requires": {
-        "mime-db": "~1.38.0"
+        "mime-db": "1.43.0"
      }
    },
    "minimatch": {
@@ -3461,9 +3443,9 @@
      "dev": true
    },
    "mixin-deep": {
-      "version": "1.3.1",
-      "resolved": "https://registry.npmjs.org/mixin-deep/-/mixin-deep-1.3.1.tgz",
-      "integrity": "sha512-8ZItLHeEgaqEvd5lYBXfm4EZSFCX29Jb9K+lAHhDKzReKBQKj3R+7NOF6tjqYi9t4oI8VUfaWITJQm86wnXGNQ==",
+      "version": "1.3.2",
+      "resolved": "https://registry.npmjs.org/mixin-deep/-/mixin-deep-1.3.2.tgz",
+      "integrity": "sha512-WRoDn//mXBiJ1H40rqa3vH0toePwSsGb45iInWlTySa+Uu4k3tYUSxa2v1KqAiLtvlrSzaExqS1gtk96A9zvEA==",
      "dev": true,
      "requires": {
        "for-in": "^1.0.2",
@@ -3559,9 +3541,9 @@
      "dev": true
    },
    "nan": {
-      "version": "2.12.1",
-      "resolved": "https://registry.npmjs.org/nan/-/nan-2.12.1.tgz",
-      "integrity": "sha512-JY7V6lRkStKcKTvHO5NVSQRv+RV+FIL5pvDoLiAtSL9pKlC5x9PKQcZDsq7m4FO4d57mkhC6Z+QhAh3Jdk5JFw==",
+      "version": "2.14.0",
+      "resolved": "https://registry.npmjs.org/nan/-/nan-2.14.0.tgz",
+      "integrity": "sha512-INOFj37C7k3AfaNTtX8RhsTw7qRy7eLET14cROi9+5HAVbbHuIWUHEauBv5qT4Av2tWasiTY1Jw6puUNqRJXQg==",
      "dev": true
    },
    "nanomatch": {
@@ -3609,45 +3591,6 @@
        "which": "1"
      },
      "dependencies": {
-        "balanced-match": {
-          "version": "1.0.0",
-          "resolved": "https://registry.npmjs.org/balanced-match/-/balanced-match-1.0.0.tgz",
-          "integrity": "sha1-ibTRmasr7kneFk6gK4nORi1xt2c=",
-          "dev": true
-        },
-        "brace-expansion": {
-          "version": "1.1.11",
-          "resolved": "https://registry.npmjs.org/brace-expansion/-/brace-expansion-1.1.11.tgz",
-          "integrity": "sha512-iCuPHDFgrHX7H2vEI/5xpz07zSHB00TpugqhmYtVmMO6518mCuRMoOYFldEBl0g187ufozdaHgWKcYFb61qGiA==",
-          "dev": true,
-          "requires": {
-            "balanced-match": "^1.0.0",
-            "concat-map": "0.0.1"
-          }
-        },
-        "glob": {
-          "version": "7.1.3",
-          "resolved": "https://registry.npmjs.org/glob/-/glob-7.1.3.tgz",
-          "integrity": "sha512-vcfuiIxogLV4DlGBHIUOwI0IbrJ8HWPc4MU7HzviGeNho/UJDfi6B5p3sHeWIQ0KGIU0Jpxi5ZHxemQfLkkAwQ==",
-          "dev": true,
-          "requires": {
-            "fs.realpath": "^1.0.0",
-            "inflight": "^1.0.4",
-            "inherits": "2",
-            "minimatch": "^3.0.4",
-            "once": "^1.3.0",
-            "path-is-absolute": "^1.0.0"
-          }
-        },
-        "minimatch": {
-          "version": "3.0.4",
-          "resolved": "https://registry.npmjs.org/minimatch/-/minimatch-3.0.4.tgz",
-          "integrity": "sha512-yJHVQEhyqPLUTgt9B83PXu6W3rx4MvvHvSUvToogpwoGDOUQ+yDrR0HRot+yOCdCO7u4hX3pWft6kWBBcqh0UA==",
-          "dev": true,
-          "requires": {
-            "brace-expansion": "^1.1.7"
-          }
-        },
        "semver": {
          "version": "5.3.0",
          "resolved": "https://registry.npmjs.org/semver/-/semver-5.3.0.tgz",
@@ -3673,9 +3616,9 @@
      }
    },
    "node-sass": {
-      "version": "4.11.0",
-      "resolved": "https://registry.npmjs.org/node-sass/-/node-sass-4.11.0.tgz",
-      "integrity": "sha512-bHUdHTphgQJZaF1LASx0kAviPH7sGlcyNhWade4eVIpFp6tsn7SV8xNMTbsQFpEV9VXpnwTTnNYlfsZXgGgmkA==",
+      "version": "4.13.1",
+      "resolved": "https://registry.npmjs.org/node-sass/-/node-sass-4.13.1.tgz",
+      "integrity": "sha512-TTWFx+ZhyDx1Biiez2nB0L3YrCZ/8oHagaDalbuBSlqXgUPsdkUSzJsVxeDO9LtPB49+Fh3WQl3slABo6AotNw==",
      "dev": true,
      "requires": {
        "async-foreach": "^0.1.3",
@@ -3685,59 +3628,16 @@
        "get-stdin": "^4.0.1",
        "glob": "^7.0.3",
        "in-publish": "^2.0.0",
-        "lodash.assign": "^4.2.0",
-        "lodash.clonedeep": "^4.3.2",
-        "lodash.mergewith": "^4.6.0",
+        "lodash": "^4.17.15",
        "meow": "^3.7.0",
        "mkdirp": "^0.5.1",
-        "nan": "^2.10.0",
+        "nan": "^2.13.2",
        "node-gyp": "^3.8.0",
        "npmlog": "^4.0.0",
        "request": "^2.88.0",
        "sass-graph": "^2.2.4",
        "stdout-stream": "^1.4.0",
        "true-case-path": "^1.0.2"
-      },
-      "dependencies": {
-        "balanced-match": {
-          "version": "1.0.0",
-          "resolved": "https://registry.npmjs.org/balanced-match/-/balanced-match-1.0.0.tgz",
-          "integrity": "sha1-ibTRmasr7kneFk6gK4nORi1xt2c=",
-          "dev": true
-        },
-        "brace-expansion": {
-          "version": "1.1.11",
-          "resolved": "https://registry.npmjs.org/brace-expansion/-/brace-expansion-1.1.11.tgz",
-          "integrity": "sha512-iCuPHDFgrHX7H2vEI/5xpz07zSHB00TpugqhmYtVmMO6518mCuRMoOYFldEBl0g187ufozdaHgWKcYFb61qGiA==",
-          "dev": true,
-          "requires": {
-            "balanced-match": "^1.0.0",
-            "concat-map": "0.0.1"
-          }
-        },
-        "glob": {
-          "version": "7.1.3",
-          "resolved": "https://registry.npmjs.org/glob/-/glob-7.1.3.tgz",
-          "integrity": "sha512-vcfuiIxogLV4DlGBHIUOwI0IbrJ8HWPc4MU7HzviGeNho/UJDfi6B5p3sHeWIQ0KGIU0Jpxi5ZHxemQfLkkAwQ==",
-          "dev": true,
-          "requires": {
-            "fs.realpath": "^1.0.0",
-            "inflight": "^1.0.4",
-            "inherits": "2",
-            "minimatch": "^3.0.4",
-            "once": "^1.3.0",
-            "path-is-absolute": "^1.0.0"
-          }
-        },
-        "minimatch": {
-          "version": "3.0.4",
-          "resolved": "https://registry.npmjs.org/minimatch/-/minimatch-3.0.4.tgz",
-          "integrity": "sha512-yJHVQEhyqPLUTgt9B83PXu6W3rx4MvvHvSUvToogpwoGDOUQ+yDrR0HRot+yOCdCO7u4hX3pWft6kWBBcqh0UA==",
-          "dev": true,
-          "requires": {
-            "brace-expansion": "^1.1.7"
-          }
-        }
      }
    },
    "nopt": {
@@ -4153,9 +4053,9 @@
          }
        },
        "lodash": {
-          "version": "4.17.11",
-          "resolved": "https://registry.npmjs.org/lodash/-/lodash-4.17.11.tgz",
-          "integrity": "sha512-cQKh8igo5QUhZ7lg38DYWAxMvjSAKG0A8wGSVimP07SIUEK2UO+arSRKbRZWtelMtN5V0Hkwh5ryOto/SshYIg==",
+          "version": "4.17.15",
+          "resolved": "https://registry.npmjs.org/lodash/-/lodash-4.17.15.tgz",
+          "integrity": "sha512-8xOcRHvCjnocdS5cpwXQXVzmmh5e5+saE2QGoeQmbKmRS6J3VQppPOIt0MnmE+4xlZoumy0GPG0D0MVIQbNA1A==",
          "dev": true
        }
      }
@@ -4229,9 +4129,9 @@
      "dev": true
    },
    "psl": {
-      "version": "1.1.31",
-      "resolved": "https://registry.npmjs.org/psl/-/psl-1.1.31.tgz",
-      "integrity": "sha512-/6pt4+C+T+wZUieKR620OpzN/LlnNKuWjy1iFLQ/UG35JqHlR/89MP1d96dUfkf6Dne3TuLQzOYEYshJ+Hx8mw==",
+      "version": "1.7.0",
+      "resolved": "https://registry.npmjs.org/psl/-/psl-1.7.0.tgz",
+      "integrity": "sha512-5NsSEDv8zY70ScRnOTn7bK7eanl2MvFrOrS/R6x+dBt5g1ghnj9Zv90kO8GwT8gxcu2ANyFprnFYB85IogIJOQ==",
      "dev": true
    },
    "punycode": {
@@ -4241,9 +4141,9 @@
      "dev": true
    },
    "puppeteer": {
-      "version": "1.12.2",
-      "resolved": "https://registry.npmjs.org/puppeteer/-/puppeteer-1.12.2.tgz",
-      "integrity": "sha512-xWSyCeD6EazGlfnQweMpM+Hs6X6PhUYhNTHKFj/axNZDq4OmrVERf70isBf7HsnFgB3zOC1+23/8+wCAZYg+Pg==",
+      "version": "1.20.0",
+      "resolved": "https://registry.npmjs.org/puppeteer/-/puppeteer-1.20.0.tgz",
+      "integrity": "sha512-bt48RDBy2eIwZPrkgbcwHtb51mj2nKvHOPMaSH2IsWiv7lOG9k9zhaRzpDZafrk05ajMc3cu+lSQYYOfH2DkVQ==",
      "dev": true,
      "requires": {
        "debug": "^4.1.0",
@@ -4266,9 +4166,9 @@
          }
        },
        "mime": {
-          "version": "2.4.0",
-          "resolved": "https://registry.npmjs.org/mime/-/mime-2.4.0.tgz",
-          "integrity": "sha512-ikBcWwyqXQSHKtciCcctu9YfPbFYZ4+gbHEmE0Q8jzcTYQg5dHCr3g2wwAZjPoJfQVXZq6KXAjpXOTf5/cjT7w==",
+          "version": "2.4.4",
+          "resolved": "https://registry.npmjs.org/mime/-/mime-2.4.4.tgz",
+          "integrity": "sha512-LRxmNwziLPT828z+4YkNzloCFC2YM4wrB99k+AV5ZbEyfGNWfG8SO1FUXLmLDBSo89NrJZ4DIWeLjy1CHGhMGA==",
          "dev": true
        }
      }
@@ -4420,14 +4320,6 @@
        "tough-cookie": "~2.4.3",
        "tunnel-agent": "^0.6.0",
        "uuid": "^3.3.2"
-      },
-      "dependencies": {
-        "extend": {
-          "version": "3.0.2",
-          "resolved": "https://registry.npmjs.org/extend/-/extend-3.0.2.tgz",
-          "integrity": "sha512-fjquC59cD7CyW6urNXK0FBufkZcoiGG80wTuPujX590cB5Ttln20E2UB4S/WARVqhXffZl2LNgS+gQdPIIim/g==",
-          "dev": true
-        }
      }
    },
    "require-directory": {
@@ -4572,47 +4464,6 @@
        "lodash": "^4.0.0",
        "scss-tokenizer": "^0.2.3",
        "yargs": "^7.0.0"
-      },
-      "dependencies": {
-        "balanced-match": {
-          "version": "1.0.0",
-          "resolved": "https://registry.npmjs.org/balanced-match/-/balanced-match-1.0.0.tgz",
-          "integrity": "sha1-ibTRmasr7kneFk6gK4nORi1xt2c=",
-          "dev": true
-        },
-        "brace-expansion": {
-          "version": "1.1.11",
-          "resolved": "https://registry.npmjs.org/brace-expansion/-/brace-expansion-1.1.11.tgz",
-          "integrity": "sha512-iCuPHDFgrHX7H2vEI/5xpz07zSHB00TpugqhmYtVmMO6518mCuRMoOYFldEBl0g187ufozdaHgWKcYFb61qGiA==",
-          "dev": true,
-          "requires": {
-            "balanced-match": "^1.0.0",
-            "concat-map": "0.0.1"
-          }
-        },
-        "glob": {
-          "version": "7.1.3",
-          "resolved": "https://registry.npmjs.org/glob/-/glob-7.1.3.tgz",
-          "integrity": "sha512-vcfuiIxogLV4DlGBHIUOwI0IbrJ8HWPc4MU7HzviGeNho/UJDfi6B5p3sHeWIQ0KGIU0Jpxi5ZHxemQfLkkAwQ==",
-          "dev": true,
-          "requires": {
-            "fs.realpath": "^1.0.0",
-            "inflight": "^1.0.4",
-            "inherits": "2",
-            "minimatch": "^3.0.4",
-            "once": "^1.3.0",
-            "path-is-absolute": "^1.0.0"
-          }
-        },
-        "minimatch": {
-          "version": "3.0.4",
-          "resolved": "https://registry.npmjs.org/minimatch/-/minimatch-3.0.4.tgz",
-          "integrity": "sha512-yJHVQEhyqPLUTgt9B83PXu6W3rx4MvvHvSUvToogpwoGDOUQ+yDrR0HRot+yOCdCO7u4hX3pWft6kWBBcqh0UA==",
-          "dev": true,
-          "requires": {
-            "brace-expansion": "^1.1.7"
-          }
-        }
      }
    },
    "scss-tokenizer": {
@@ -4773,9 +4624,9 @@
      "dev": true
    },
    "set-value": {
-      "version": "2.0.0",
-      "resolved": "https://registry.npmjs.org/set-value/-/set-value-2.0.0.tgz",
-      "integrity": "sha512-hw0yxk9GT/Hr5yJEYnHNKYXkIA8mVJgd9ditYZCe16ZczcaELYYcfvaXesNACk2O8O0nTiPQcQhGUQj8JLzeeg==",
+      "version": "2.0.1",
+      "resolved": "https://registry.npmjs.org/set-value/-/set-value-2.0.1.tgz",
+      "integrity": "sha512-JxHc1weCN68wRY0fhCoXpyK55m/XPHafOmK4UWD7m2CI14GMcFypt4w/0+NV5f/ZMby2F6S2wwA7fgynh9gWSw==",
      "dev": true,
      "requires": {
        "extend-shallow": "^2.0.1",
@@ -5248,13 +5099,13 @@
      "dev": true
    },
    "tar": {
-      "version": "2.2.1",
-      "resolved": "https://registry.npmjs.org/tar/-/tar-2.2.1.tgz",
-      "integrity": "sha1-jk0qJWwOIYXGsYrWlK7JaLg8sdE=",
+      "version": "2.2.2",
+      "resolved": "https://registry.npmjs.org/tar/-/tar-2.2.2.tgz",
+      "integrity": "sha512-FCEhQ/4rE1zYv9rYXJw/msRqsnmlje5jHP6huWeBZ704jUTy02c5AZyWujpMR1ax6mVw9NyJMfuK2CMDWVIfgA==",
      "dev": true,
      "requires": {
        "block-stream": "*",
-        "fstream": "^1.0.2",
+        "fstream": "^1.0.12",
        "inherits": "2"
      }
    },
@@ -5379,26 +5230,10 @@
        "glob": "^7.1.2"
      },
      "dependencies": {
-        "balanced-match": {
-          "version": "1.0.0",
-          "resolved": "https://registry.npmjs.org/balanced-match/-/balanced-match-1.0.0.tgz",
-          "integrity": "sha1-ibTRmasr7kneFk6gK4nORi1xt2c=",
-          "dev": true
-        },
-        "brace-expansion": {
-          "version": "1.1.11",
-          "resolved": "https://registry.npmjs.org/brace-expansion/-/brace-expansion-1.1.11.tgz",
-          "integrity": "sha512-iCuPHDFgrHX7H2vEI/5xpz07zSHB00TpugqhmYtVmMO6518mCuRMoOYFldEBl0g187ufozdaHgWKcYFb61qGiA==",
-          "dev": true,
-          "requires": {
-            "balanced-match": "^1.0.0",
-            "concat-map": "0.0.1"
-          }
-        },
        "glob": {
-          "version": "7.1.3",
-          "resolved": "https://registry.npmjs.org/glob/-/glob-7.1.3.tgz",
-          "integrity": "sha512-vcfuiIxogLV4DlGBHIUOwI0IbrJ8HWPc4MU7HzviGeNho/UJDfi6B5p3sHeWIQ0KGIU0Jpxi5ZHxemQfLkkAwQ==",
+          "version": "7.1.6",
+          "resolved": "https://registry.npmjs.org/glob/-/glob-7.1.6.tgz",
+          "integrity": "sha512-LwaxwyZ72Lk7vZINtNNrywX0ZuLyStrdDtabefZKAY5ZGJhVtgdznluResxNmPitE0SAO+O26sWTHeKSI2wMBA==",
          "dev": true,
          "requires": {
            "fs.realpath": "^1.0.0",
@@ -5488,38 +5323,15 @@
      }
    },
    "union-value": {
-      "version": "1.0.0",
-      "resolved": "https://registry.npmjs.org/union-value/-/union-value-1.0.0.tgz",
-      "integrity": "sha1-XHHDTLW61dzr4+oM0IIHulqhrqQ=",
+      "version": "1.0.1",
+      "resolved": "https://registry.npmjs.org/union-value/-/union-value-1.0.1.tgz",
+      "integrity": "sha512-tJfXmxMeWYnczCVs7XAEvIV7ieppALdyepWMkHkwciRpZraG/xwT+s2JN8+pr1+8jCRf80FFzvr+MpQeeoF4Xg==",
      "dev": true,
      "requires": {
        "arr-union": "^3.1.0",
        "get-value": "^2.0.6",
        "is-extendable": "^0.1.1",
-        "set-value": "^0.4.3"
-      },
-      "dependencies": {
-        "extend-shallow": {
-          "version": "2.0.1",
-          "resolved": "https://registry.npmjs.org/extend-shallow/-/extend-shallow-2.0.1.tgz",
-          "integrity": "sha1-Ua99YUrZqfYQ6huvu5idaxxWiQ8=",
-          "dev": true,
-          "requires": {
-            "is-extendable": "^0.1.0"
-          }
-        },
-        "set-value": {
-          "version": "0.4.3",
-          "resolved": "https://registry.npmjs.org/set-value/-/set-value-0.4.3.tgz",
-          "integrity": "sha1-fbCPnT0i3H945Trzw79GZuzfzPE=",
-          "dev": true,
-          "requires": {
-            "extend-shallow": "^2.0.1",
-            "is-extendable": "^0.1.1",
-            "is-plain-object": "^2.0.1",
-            "to-object-path": "^0.3.0"
-          }
-        }
+        "set-value": "^2.0.1"
      }
    },
    "unpipe": {
@@ -5649,9 +5461,9 @@
      "dev": true
    },
    "uuid": {
-      "version": "3.3.2",
-      "resolved": "https://registry.npmjs.org/uuid/-/uuid-3.3.2.tgz",
-      "integrity": "sha512-yXJmeNaw3DnnKAOKJE51sL/ZaYfWJRl1pK9dr19YFCu0ObS231AB1/LbqTKRAQ5kw8A90rA6fr4riOUpTZvQZA==",
+      "version": "3.4.0",
+      "resolved": "https://registry.npmjs.org/uuid/-/uuid-3.4.0.tgz",
+      "integrity": "sha512-HjSDRw6gZE5JMggctHBcjVak08+KEVhSIiDzFnT9S9aegmp85S/bReBVTb4QTFaRNptJ9kuYaNhnbNEOkbKb/A==",
      "dev": true
    },
    "v8flags": {
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
  "name": "reveal.js",
-  "version": "3.8.0",
+  "version": "3.9.2",
  "description": "The HTML Presentation Framework",
  "homepage": "http://revealjs.com",
  "subdomain": "revealjs",
@@ -25,8 +25,8 @@
  "devDependencies": {
    "express": "^4.16.2",
    "grunt": "^1.0.4",
-    "grunt-cli": "^1.3.2",
    "grunt-autoprefixer": "^3.0.4",
+    "grunt-cli": "^1.3.2",
    "grunt-contrib-connect": "^2.0.0",
    "grunt-contrib-cssmin": "^3.0.0",
    "grunt-contrib-jshint": "^2.0.0",
@@ -36,8 +36,8 @@
    "grunt-sass": "^3.0.2",
    "grunt-zip": "~0.17.1",
    "load-grunt-tasks": "^4.0.0",
-    "node-sass": "^4.11.0",
    "mustache": "^2.3.0",
+    "node-sass": "^4.13.1",
    "socket.io": "^2.2.0"
  },
  "license": "MIT"
--- a/plugin/highlight/highlight.js
+++ b/plugin/highlight/highlight.js
--- a/plugin/notes/notes.html
+++ b/plugin/notes/notes.html
@@ -539,12 +539,17 @@

 					callRevealApi( 'getSlidesAttributes', [], function ( slideAttributes ) {
 						callRevealApi( 'getConfig', [], function ( config ) {
+							var totalTime = config.totalTime;
+							var minTimePerSlide = config.minimumTimePerSlide || 0;
 							var defaultTiming = config.defaultTiming;
-							if (defaultTiming == null) {
+							if ((defaultTiming == null) && (totalTime == null)) {
 								callback(null);
 								return;
 							}
-
+							// Setting totalTime overrides defaultTiming
+							if (totalTime) {
+								defaultTiming = 0;
+							}
 							var timings = [];
 							for ( var i in slideAttributes ) {
 								var slide = slideAttributes[ i ];
@@ -559,7 +564,22 @@
 								}
 								timings.push(timing);
 							}
-
+							if ( totalTime ) {
+								// After we've allocated time to individual slides, we summarize it and
+								// subtract it from the total time
+								var remainingTime = totalTime - timings.reduce( function(a, b) { return a + b; }, 0 );
+								// The remaining time is divided by the number of slides that have 0 seconds
+								// allocated at the moment, giving the average time-per-slide on the remaining slides
+								var remainingSlides = (timings.filter( function(x) { return x == 0 }) ).length
+								var timePerSlide = Math.round( remainingTime / remainingSlides, 0 )
+								// And now we replace every zero-value timing with that average
+								timings = timings.map( function(x) { return (x==0 ? timePerSlide : x) } );
+							}
+							var slidesUnderMinimum = timings.filter( function(x) { return (x < minTimePerSlide) } ).length
+							if ( slidesUnderMinimum ) {
+								message = "The pacing time for " + slidesUnderMinimum + " slide(s) is under the configured minimum of " + minTimePerSlide + " seconds. Check the data-timing attribute on individual slides, or consider increasing the totalTime or minimumTimePerSlide configuration options (or removing some slides).";
+								alert(message);
+							}
 							callback( timings );
 						} );
 					} );
--- a/test/test-iframe-backgrounds.html
+++ b/test/test-iframe-backgrounds.html
@@ -0,0 +1,104 @@
+<!doctype html>
+<html lang="en">
+
+	<head>
+		<meta charset="utf-8">
+
+		<title>reveal.js - Test Iframe Backgrounds</title>
+
+		<link rel="stylesheet" href="../css/reveal.css">
+		<link rel="stylesheet" href="qunit-2.5.0.css">
+	</head>
+
+	<body style="overflow: auto;">
+
+		<div id="qunit"></div>
+		<div id="qunit-fixture"></div>
+
+		<div class="reveal" style="display: none;">
+
+			<div class="slides">
+
+				<section data-background-iframe="#1">1</section>
+				<section data-background-iframe="#2">2</section>
+				<section data-background-iframe="#3" data-preload>3</section>
+				<section data-background-iframe="#4">4</section>
+				<section data-background-iframe="#5">5</section>
+				<section data-background-iframe="#6">6</section>
+
+			</div>
+
+		</div>
+
+		<script src="../js/reveal.js"></script>
+		<script src="qunit-2.5.0.js"></script>
+
+		<script>
+
+
+			Reveal.addEventListener( 'ready', function() {
+
+				function getIframe( index ) {
+					return document.querySelectorAll( '.slide-background' )[index].querySelector( 'iframe' );
+				}
+
+				QUnit.module( 'Iframe' );
+
+				QUnit.test( 'Using default settings', function( assert ) {
+
+					Reveal.slide(0);
+					assert.strictEqual( getIframe(1).hasAttribute( 'src' ), false, 'not preloaded when within viewDistance' );
+
+					Reveal.slide(1);
+					assert.strictEqual( getIframe(1).hasAttribute( 'src' ), true, 'loaded when slide becomes visible' );
+
+					Reveal.slide(0);
+					assert.strictEqual( getIframe(1).hasAttribute( 'src' ), false, 'unloaded when slide becomes invisible' );
+
+				});
+
+				QUnit.test( 'Using data-preload', function( assert ) {
+
+					Reveal.slide(1);
+					assert.strictEqual( getIframe(2).hasAttribute( 'src' ), true, 'preloaded within viewDistance' );
+					assert.strictEqual( getIframe(1).hasAttribute( 'src' ), true, 'loaded when slide becomes visible' );
+
+					Reveal.slide(0);
+					assert.strictEqual( getIframe(3).hasAttribute( 'src' ), false, 'unloads outside of viewDistance' );
+
+				});
+
+				QUnit.test( 'Using preloadIframes: true', function( assert ) {
+
+					Reveal.configure({ preloadIframes: true });
+
+					Reveal.slide(1);
+					assert.strictEqual( getIframe(0).hasAttribute( 'src' ), true, 'preloaded within viewDistance' );
+					assert.strictEqual( getIframe(1).hasAttribute( 'src' ), true, 'preloaded within viewDistance' );
+					assert.strictEqual( getIframe(2).hasAttribute( 'src' ), true, 'preloaded within viewDistance' );
+
+				});
+
+				QUnit.test( 'Using preloadIframes: false', function( assert ) {
+
+					Reveal.configure({ preloadIframes: false });
+
+					Reveal.slide(0);
+					assert.strictEqual( getIframe(1).hasAttribute( 'src' ), false, 'not preloaded within viewDistance' );
+					assert.strictEqual( getIframe(2).hasAttribute( 'src' ), false, 'not preloaded within viewDistance' );
+
+					Reveal.slide(1);
+					assert.strictEqual( getIframe(1).hasAttribute( 'src' ), true, 'loaded when slide becomes visible' );
+
+
+				});
+
+			} );
+
+			Reveal.initialize({
+				viewDistance: 3
+			});
+		</script>
+
+	</body>
+</html>
--- a/test/test.js
+++ b/test/test.js
@@ -250,6 +250,22 @@ Reveal.addEventListener( 'ready', function() {
 		assert.deepEqual( Reveal.getIndices(), { h: 2, v: 0, f: 1 }, 'Reveal.slide( 2, 0, 1 )' );
 	});

+	QUnit.test( 'data-fragment is set on slide <section>', function( assert ) {
+		Reveal.slide( 2, 0, -1 );
+		assert.deepEqual( Reveal.getCurrentSlide().getAttribute( 'data-fragment' ), '-1' );
+
+		Reveal.slide( 2, 0, 2 );
+		assert.deepEqual( Reveal.getCurrentSlide().getAttribute( 'data-fragment' ), '2' );
+
+		Reveal.slide( 2, 0, 0 );
+		assert.deepEqual( Reveal.getCurrentSlide().getAttribute( 'data-fragment' ), '0' );
+
+		var fragmentSlide = Reveal.getCurrentSlide();
+
+		Reveal.slide( 3, 0 );
+		assert.deepEqual( fragmentSlide.getAttribute( 'data-fragment' ), '0', 'data-fragment persists when jumping to another slide' );
+	});
+
 	QUnit.test( 'Hiding all fragments', function( assert ) {
 		var fragmentSlide = document.querySelector( '#fragment-slides>section:nth-child(1)' );
Author	SHA1	Message	Date
Hakim El Hattab	94d98ff7d8	3.9.2 security release	2020-01-31 11:11:23 +01:00
Hakim El Hattab	b6cc6b4916	blacklist some method from the postMessage API to prevent XSS	2020-01-31 10:59:41 +01:00
Hakim El Hattab	d213fac34c	add note about supporting reveal.js via Slides	2020-01-30 10:15:39 +01:00
Hakim El Hattab	eaf3988311	3.9.1 because a local edit made it into npm	2020-01-29 15:11:49 +01:00
Hakim El Hattab	003a848790	update to highlight.js 9.18.0 #2562	2020-01-29 14:51:28 +01:00
Hakim El Hattab	33ed32c4f0	add step-by-step highlights to readme	2020-01-29 14:01:51 +01:00
Hakim El Hattab	8a54118f43	npm audit fix 😶	2020-01-27 14:50:54 +01:00
Hakim El Hattab	45f468ccc4	3.9.0	2020-01-27 14:47:17 +01:00
Hakim El Hattab	a59b1415f8	Merge branch 'pdf-slide-numbers' of https://github.com/dougalsutherland/reveal.js into dev	2020-01-27 14:10:15 +01:00
Hakim El Hattab	281b518620	Merge pull request #2499 from jocaml/patch-1 Fix which node version is required	2020-01-27 13:51:38 +01:00
Hakim El Hattab	9693816480	Merge branch 'dev' into patch-1	2020-01-27 13:51:24 +01:00
Hakim El Hattab	731f6819ac	Merge pull request #2567 from trevorpower/patch-1 fixed link to gruntfile	2020-01-27 13:46:34 +01:00
Hakim El Hattab	d969ec5f25	2020	2020-01-15 11:39:19 +01:00
Hakim El Hattab	ac50753521	add data-fragment=<index> attribute to slide <sections>	2020-01-15 11:37:37 +01:00
Trevor Power	76a8193fc2	fixed link to gruntfile	2020-01-13 11:57:17 +00:00
Hakim El Hattab	76187bc666	Merge pull request #2474 from coliff/patch-1 HTTPS relevant links on README	2020-01-11 20:51:56 +01:00
Hakim El Hattab	dbf575f8db	Merge pull request #2483 from Adri-May/bugfix/spelling Bug fix: spelling errors	2020-01-11 20:51:01 +01:00
Hakim El Hattab	7a169732de	upgrade to node-sass 4.13.0, fix security warnings #2473	2020-01-11 20:30:29 +01:00
Hakim El Hattab	6f9b10b269	switch to fixed unit for fragment animations to make them more consistent	2019-12-19 08:16:42 +01:00
Hakim El Hattab	201e8316a2	Merge pull request #2437 from TehDmitry/dev Allowing autoplay in data-background-iframe for audio and video elements	2019-12-09 21:09:38 +01:00
Hakim El Hattab	bb8b4d8883	Merge pull request #2454 from ismailarilik/patch-1 Add forgotten element to Table of Contents	2019-12-09 21:06:53 +01:00
Hakim El Hattab	94de806f06	add mobileViewDistance to readme #2513	2019-12-09 21:05:41 +01:00
Hakim El Hattab	1515ddcf87	Merge pull request #2513 from TuurDutoit/feature/mobile-view-distance Add mobileViewDistance config key	2019-12-09 21:00:58 +01:00
Dougal J. Sutherland	c189a21efd	honor slide number config in pdf mode	2019-10-29 12:48:21 -05:00
Dougal J. Sutherland	1cf5ffe029	add a slide argument to locationHash(), getSlidePastCount()	2019-10-29 12:48:21 -05:00
Tuur Dutoit	6ab72eae51	Add mobileViewDistance config key	2019-10-18 13:37:16 +02:00
Hakim El Hattab	f9affb550a	fix viewport overflow in iPadOS safari	2019-10-11 09:23:44 +02:00
Hrvoje Bandov	6979383e4b	Fix which node version is required In `package.json` engine is set to `>=9.0.0`.	2019-10-08 09:29:59 +02:00
Adri-May	02a42d1c9e	Bug fix: spelling errors	2019-09-18 21:57:24 -04:00
Christian Oliff	a458676614	HTTPS relevant links on README	2019-09-03 10:59:33 +09:00
Hakim El Hattab	474731d829	highlight.js 9.11 -> 9.15	2019-08-22 13:21:12 +02:00
İsmail Arılık	52e57d3677	Add forgotten element to Table of Contents	2019-07-12 14:38:53 +03:00
Hakim El Hattab	073d0e3358	Merge pull request #2392 from DanielNoga/patch-1 update minimal nodejs version in readme	2019-07-08 10:07:53 +02:00
Hakim El Hattab	07c20ef9d9	Merge pull request #2442 from pius/patch-1 Tweak to MathJax example	2019-07-08 10:06:04 +02:00
Hakim El Hattab	d5662a203e	Merge branch 'dev' into patch-1	2019-07-08 10:05:40 +02:00
Hakim El Hattab	a6f1511d1a	Merge pull request #2453 from Incognitas/fix/node_12_support Update package.json for node 12 support	2019-07-08 10:02:30 +02:00
Hakim El Hattab	cf027f21c6	Merge pull request #2451 from Jason-Cooke/patch-1 docs: fix typo	2019-07-08 10:01:55 +02:00
Aurelien Normand	585aafed95	Adding missing file to use it properly	2019-07-07 15:30:31 +02:00
Aurélien Normand	0935462706	Update package.json for node 12 support simple node-sass update which fixes this issue	2019-07-07 11:41:30 +02:00
Jason Cooke	1bacb27072	docs: fix typo	2019-07-05 22:00:10 +12:00
Pius Uzamere	abac58cfc5	Tweak to MathJax example Added a missing comma and used an actual macro so that the MathJax example runs right out of the box upon a copy/paste.	2019-06-22 15:17:01 -04:00
Hakim El Hattab	bd3758a4df	readme tweak	2019-06-10 07:41:07 +02:00
Hakim El Hattab	5fb743e65e	rephrased #2378	2019-06-10 07:38:57 +02:00
Hakim El Hattab	c92d08acdd	Merge pull request #2378 from mbotsch/fix-plugin-documentation Fix plugin documentation regarding init-Promises	2019-06-10 07:34:21 +02:00
Hakim El Hattab	ff2a927de8	Merge pull request #2433 from autopp/fix-typo-in-readme add missing comma to MathJax example in README	2019-06-10 07:19:57 +02:00
Hakim El Hattab	bba760e549	remove available route changes #2416	2019-06-10 07:14:04 +02:00
Hakim El Hattab	51e8da5d9a	Merge branch '2380-linear-navigation-mobile' of https://github.com/earboxer/reveal.js into dev	2019-06-10 07:04:49 +02:00
Hakim El Hattab	f6f7f28ad9	enable url hash for default index.html #2434 #2175	2019-06-10 06:57:07 +02:00
TehDmitry	bdda443335	Allowing autoplay in data-background-iframe for audio and video elements It was restricted by «Autoplay Policy Changes»: https://developers.google.com/web/updates/2017/09/autoplay-policy-changes#iframe	2019-06-09 16:31:36 +03:00
autopp	f5759c3d52	add missing comma to MathJax example in README	2019-06-07 09:45:20 +09:00
Zach DeCook	969e7b3ef1	* Mobile Linear Navigation: Fix swipes to navigate linearly	2019-05-29 10:44:43 -04:00
Zach DeCook	c62f4c7cfb	* Linear Navigation: Fix showing arrows when last slide has vertical children	2019-05-29 10:22:15 -04:00
Hakim El Hattab	99c3498253	first/last slide shortcut now uses shift modified, cmd conflicted with browser back/fwd	2019-05-27 08:45:00 +02:00
Hakim El Hattab	25e521a16c	Merge branch 'alternate-timing' of https://github.com/fghaas/reveal.js into dev	2019-05-27 08:08:00 +02:00
Hakim El Hattab	a1dd1028a1	down arrow padding for edge aligned controls	2019-05-27 08:04:58 +02:00
Hakim El Hattab	9108519dc1	Merge pull request #2410 from NoriSte/feature/fix-touch-arrow-down Fix arrow down navigation on touch devices	2019-05-27 07:56:15 +02:00
Hakim El Hattab	a2e9e525d5	avoid exception when highlighting empty code blocks	2019-05-27 07:30:08 +02:00
Florian Haas	23c12d7332	Notes: Weakly enforce a minimum allocated pacing time per slide When using the totalTime-based pacing calculation, a presenter may inadvertently set totalTime and per-slide data-timing attributes in such a way that the pacing time for some slides is impossibly low or even negative. Add a check to ensure that the pacing on a slide never falls below a configurable minimum, defaulting to 0. Display an alert if the pacing for any slide(s) falls below the threshold.	2019-05-22 21:44:44 +02:00
Hakim El Hattab	9ac654d584	fix issue where syncSlide would not run/play newly added background content	2019-05-20 14:58:52 +02:00
Hakim El Hattab	bd1e82d19a	new API methods for getting horizontal/vertical slides, force linear navigation for one-dimensional decks	2019-05-20 11:24:05 +02:00
NoriSte	6ac01281d2	fix the touch devices issues with the down arrow	2019-05-18 12:57:35 +02:00
Hakim El Hattab	1766e37a63	iframe background preload behavior now matches inline iframes + adheres to the new 'preloadIframes' config option	2019-05-13 10:55:29 +02:00
Florian Haas	078ba62050	Notes: Introduce alternate pacing timer, based on total presentation time The current pacing timer operates on the assumption that there is a default amount of time to be allocated to each slide, and that individual slides can deviate from that default by specifying their own data-timing attribute. This patch introduces an alternate pacing method: by specifying the totalTime configuration option, the presenter can set the total time available to present. The pacing timer will then continue to allocate the exact pacing time for slides that do have data-timing set, as before. However, rather than applying the defaultTiming constant to all others, it will - Add up the time already allocated to slides via data-timing; - subtract that from totalTime; - divide the difference by the number of slides without data-timing set; - apply the thus-calculated average to those slides. totalTime has no default, and if both defaultTiming and totalTime are set, totalTime wins. This preserves backward compatibility: if a presenter has set defaultTiming and updates reveal.js, totalTime will be null and defaultTiming is still applied to all slides without a data-timing attribute. The presenter can then switch to the automatic calculation, if desired, by setting a value for totalTime.	2019-05-12 20:10:06 +02:00
Daniel Noga	39ed39f3e2	update minimal nodejs version in readme	2019-05-05 13:34:43 +02:00
Mario Botsch	1f5fb971d4	Fix plugin documentation Mention that reveal.js will wait for the Promise of a plugin's init() function only when the plugin is loaded non-async. The init functions of plugins that are loaded as async dependencies are called after reveal.js has dispatched the 'ready' event.	2019-04-23 23:28:05 +02:00
Hakim El Hattab	a16b71a981	the postMessage API now works for getter methods	2019-04-23 10:52:45 +02:00
Hakim El Hattab	32197bd77d	fix numeric presence condition	2019-04-10 10:09:41 +02:00
Richard Westenra	33bed47dac	Remove calls to missing modules from gruntfile When running the app, Grunt throws the following warnings: >> Local Npm module "grunt-contrib-clean" not found. Is it installed? >> Local Npm module "grunt-contrib-nodeunit" not found. Is it installed? These modules don't appear to do anything except throw a warning so they can probably just be removed.	2019-04-08 10:36:33 +02:00
Hakim El Hattab	9aa514bc70	Merge pull request #2364 from richardwestenra/fix/missing-modules Bugfix: Remove calls to missing modules from gruntfile	2019-04-08 10:14:02 +02:00
Richard Westenra	3ff070536e	Remove calls to missing modules from gruntfile When running the app, Grunt throws the following warnings: >> Local Npm module "grunt-contrib-clean" not found. Is it installed? >> Local Npm module "grunt-contrib-nodeunit" not found. Is it installed? These modules don't appear to do anything except throw a warning so they can probably just be removed.	2019-04-06 11:07:05 +03:00
Hakim El Hattab	e9ba289e80	refinements for multi-step code highlights	2019-04-05 19:49:17 +02:00
Hakim El Hattab	7eb2cec6b6	first version of multi-step code highlights	2019-04-05 07:59:35 +02:00
Hakim El Hattab	c636b88b2d	Merge branch 'master' of github.com:hakimel/reveal.js into dev	2019-04-03 10:49:22 +02:00
Hakim El Hattab	3643112b35	plugin doc tweaks	2019-04-03 10:49:14 +02:00
Hakim El Hattab	4c557a5959	prefer transform scaling over zoom on hdpi displays	2019-04-02 16:25:27 +02:00
Hakim El Hattab	15dec96e73	better example for line range highlighting	2019-04-01 15:48:46 +02:00
Hakim El Hattab	da4ec074f1	docs for code highlight line numbering	2019-04-01 15:45:07 +02:00
Hakim El Hattab	485870946f	plugin docs	2019-04-01 15:25:40 +02:00
Hakim El Hattab	25c504c22f	plugin api docs	2019-04-01 15:11:51 +02:00