README.md

# reveal.js [![Build Status](https://travis-ci.org/hakimel/reveal.js.svg?branch=master)](https://travis-ci.org/hakimel/reveal.js)

A framework for easily creating beautiful presentations using HTML. [Check out the live demo](http://lab.hakim.se/reveal-js/).

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). It's best viewed in a modern browser but [fallbacks](https://github.com/hakimel/reveal.js/wiki/Browser-Support) are available to make sure your presentation can still be viewed elsewhere.


#### More reading:
- [Installation](#installation): Step-by-step instructions for getting reveal.js running on your computer.
- [Changelog](https://github.com/hakimel/reveal.js/releases): Up-to-date version history.
- [Examples](https://github.com/hakimel/reveal.js/wiki/Example-Presentations): Presentations created with reveal.js, add your own!
- [Browser Support](https://github.com/hakimel/reveal.js/wiki/Browser-Support): Explanation of browser support and fallbacks.
- [Plugins](https://github.com/hakimel/reveal.js/wiki/Plugins,-Tools-and-Hardware): A list of plugins that can be used to extend reveal.js.

## Online Editor

Presentations are written using HTML or Markdown but there's also an online editor for those of you who prefer a graphical interface. Give it a try at [http://slides.com](http://slides.com).


## Instructions

### Markup

Markup hierarchy needs to be ``<div class="reveal"> <div class="slides"> <section>`` where the ``<section>`` represents one slide and can be repeated indefinitely. If you place multiple ``<section>``'s inside of another ``<section>`` they will be shown as vertical slides. The first of the vertical slides is the "root" of the others (at the top), and it will be included in the horizontal sequence. For example:

```html
<div class="reveal">
	<div class="slides">
		<section>Single Horizontal Slide</section>
		<section>
			<section>Vertical Slide 1</section>
			<section>Vertical Slide 2</section>
		</section>
	</div>
</div>
```

### Markdown

It's possible to write your slides using Markdown. To enable Markdown, add the ```data-markdown``` attribute to your ```<section>``` elements and wrap the contents in a ```<script type="text/template">``` like the example below.

This is based on [data-markdown](https://gist.github.com/1343518) from [Paul Irish](https://github.com/paulirish) modified to use [marked](https://github.com/chjj/marked) to support [Github Flavoured Markdown](https://help.github.com/articles/github-flavored-markdown). Sensitive to indentation (avoid mixing tabs and spaces) and line breaks (avoid consecutive breaks).

```html
<section data-markdown>
	<script type="text/template">
		## Page title

		A paragraph with some text and a [link](http://hakim.se).
	</script>
</section>
```

#### External Markdown

You can write your content as a separate file and have reveal.js load it at runtime. Note the separator arguments which determine how slides are delimited in the external file. The ```data-charset``` attribute is optional and specifies which charset to use when loading the external file.

When used locally, this feature requires that reveal.js [runs from a local web server](#full-setup).

```html
<section data-markdown="example.md"  
         data-separator="^\n\n\n"  
         data-separator-vertical="^\n\n"  
         data-separator-notes="^Note:"  
         data-charset="iso-8859-15">
</section>
```

#### Element Attributes

Special syntax (in html comment) is available for adding attributes to Markdown elements. This is useful for fragments, amongst other things.

```html
<section data-markdown>
	<script type="text/template">
		- Item 1 <!-- .element: class="fragment" data-fragment-index="2" -->
		- Item 2 <!-- .element: class="fragment" data-fragment-index="1" -->
	</script>
</section>
```

#### Slide Attributes

Special syntax (in html comment) is available for adding attributes to the slide `<section>` elements generated by your Markdown.

```html
<section data-markdown>
	<script type="text/template">
	<!-- .slide: data-background="#ff0000" -->
		Markdown content
	</script>
</section>
```


### Configuration

At the end of your page you need to initialize reveal by running the following code. Note that all config values are optional and will default as specified below.

```javascript
Reveal.initialize({

	// Display controls in the bottom right corner
	controls: true,

	// Display a presentation progress bar
	progress: true,

	// Display the page number of the current slide
	slideNumber: false,

	// Push each slide change to the browser history
	history: false,

	// Enable keyboard shortcuts for navigation
	keyboard: true,

	// Enable the slide overview mode
	overview: true,

	// Vertical centering of slides
	center: true,

	// Enables touch navigation on devices with touch input
	touch: true,

	// Loop the presentation
	loop: false,

	// Change the presentation direction to be RTL
	rtl: false,

	// Turns fragments on and off globally
	fragments: true,

	// Flags if the presentation is running in an embedded mode,
	// i.e. contained within a limited portion of the screen
	embedded: false,

	// Flags if we should show a help overlay when the questionmark
	// key is pressed
	help: true,

	// Number of milliseconds between automatically proceeding to the
	// next slide, disabled when set to 0, this value can be overwritten
	// by using a data-autoslide attribute on your slides
	autoSlide: 0,

	// Stop auto-sliding after user input
	autoSlideStoppable: true,

	// Enable slide navigation via mouse wheel
	mouseWheel: false,

	// Hides the address bar on mobile devices
	hideAddressBar: true,

	// Opens links in an iframe preview overlay
	previewLinks: false,

	// Transition style
	transition: 'default', // none/fade/slide/convex/concave/zoom

	// Transition speed
	transitionSpeed: 'default', // default/fast/slow

	// Transition style for full page slide backgrounds
	backgroundTransition: 'default', // none/fade/slide/convex/concave/zoom

	// Number of slides away from the current that are visible
	viewDistance: 3,

	// Parallax background image
	parallaxBackgroundImage: '', // e.g. "'https://s3.amazonaws.com/hakim-static/reveal-js/reveal-parallax-1.jpg'"

	// Parallax background size
	parallaxBackgroundSize: '', // CSS syntax, e.g. "2100px 900px"

	// Amount to move parallax background (horizontal and vertical) on slide change
	// Number, e.g. 100
	parallaxBackgroundHorizontal: '',
	parallaxBackgroundVertical: ''

});
```


The configuration can be updated after initialization using the ```configure``` method:

```javascript
// Turn autoSlide off
Reveal.configure({ autoSlide: 0 });

// Start auto-sliding every 5s
Reveal.configure({ autoSlide: 5000 });
```


### Dependencies

Reveal.js doesn't _rely_ on any third party scripts to work but a few optional libraries are included by default. These libraries are loaded as dependencies in the order they appear, for example:

```javascript
Reveal.initialize({
	dependencies: [
		// Cross-browser shim that fully implements classList - https://github.com/eligrey/classList.js/
		{ src: 'lib/js/classList.js', condition: function() { return !document.body.classList; } },

		// Interpret Markdown in <section> elements
		{ src: 'plugin/markdown/marked.js', condition: function() { return !!document.querySelector( '[data-markdown]' ); } },
		{ 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(); } },

		// Zoom in and out with Alt+click
		{ src: 'plugin/zoom-js/zoom.js', async: true },

		// Speaker notes
		{ src: 'plugin/notes/notes.js', async: true },

		// Remote control your reveal.js presentation using a touch device
		{ src: 'plugin/remotes/remotes.js', async: true },

		// MathJax
		{ src: 'plugin/math/math.js', async: true }
	]
});
```

You can add your own extensions using the same syntax. The following properties are available for each dependency object:
- **src**: Path to the script to load
- **async**: [optional] Flags if the script should load after reveal.js has started, defaults to false
- **callback**: [optional] Function to execute when the script has loaded
- **condition**: [optional] Function which must return true for the script to be loaded


### Ready Event

A 'ready' event is fired when reveal.js has loaded all non-async dependencies and is ready to start navigating. To check if reveal.js is already 'ready' you can call `Reveal.isReady()`.

```javascript
Reveal.addEventListener( 'ready', function( event ) {
	// event.currentSlide, event.indexh, event.indexv
} );
```


### Presentation Size

All presentations have a normal size, that is the resolution at which they are authored. The framework will automatically scale presentations uniformly based on this size to ensure that everything fits on any given display or viewport.

See below for a list of configuration options related to sizing, including default values:

```javascript
Reveal.initialize({

	...

	// The "normal" size of the presentation, aspect ratio will be preserved
	// when the presentation is scaled to fit different resolutions. Can be
	// specified using percentage units.
	width: 960,
	height: 700,

	// Factor of the display size that should remain empty around the content
	margin: 0.1,

	// Bounds for smallest/largest possible scale to apply to content
	minScale: 0.2,
	maxScale: 1.5

});
```


### Auto-sliding

Presentations can be configured to progress through slides automatically, without any user input. To enable this you will need to tell the framework how many milliseconds it should wait between slides:

```javascript
// Slide every five seconds
Reveal.configure({
  autoSlide: 5000
});
```
When this is turned on a control element will appear that enables users to pause and resume auto-sliding. Alternatively, sliding can be paused or resumed by pressing »a« on the keyboard. Sliding is paused automatically as soon as the user starts navigating. You can disable these controls by specifying ```autoSlideStoppable: false``` in your reveal.js config.

You can also override the slide duration for individual slides and fragments by using the ```data-autoslide``` attribute:

```html
<section data-autoslide="2000">
	<p>After 2 seconds the first fragment will be shown.</p>
	<p class="fragment" data-autoslide="10000">After 10 seconds the next fragment will be shown.</p>
	<p class="fragment">Now, the fragment is displayed for 2 seconds before the next slide is shown.</p>
</section>
```

Whenever the auto-slide mode is resumed or paused the ```autoslideresumed``` and ```autoslidepaused``` events are fired.


### Keyboard Bindings

If you're unhappy with any of the default keyboard bindings you can override them using the ```keyboard``` config option:

```javascript
Reveal.configure({
  keyboard: {
    13: 'next', // go to the next slide when the ENTER key is pressed
    27: function() {}, // do something custom when ESC is pressed
    32: null // don't do anything when SPACE is pressed (i.e. disable a reveal.js default binding)
  }
});
```

### Lazy Loading

When working on presentation with a lot of media or iframe content it's important to load lazily. Lazy loading means that reveal.js will only load content for the few slides nearest to the current slide. The number of slides that are preloaded is determined by the `viewDistance` configuration option.

To enable lazy loading all you need to do is change your "src" attributes to "data-src" as shown below. This is supported for image, video, audio and iframe elements. Lazy loaded iframes will also unload when the containing slide is no longer visible.

```html
<section>
  <img data-src="image.png">
  <iframe data-src="http://hakim.se"></iframe>
  <video>
    <source data-src="video.webm" type="video/webm" />
    <source data-src="video.mp4" type="video/mp4" />
  </video>
</section>
```


### API

The ``Reveal`` object exposes a JavaScript API for controlling navigation and reading state:

```javascript
// Navigation
Reveal.slide( indexh, indexv, indexf );
Reveal.left();
Reveal.right();
Reveal.up();
Reveal.down();
Reveal.prev();
Reveal.next();
Reveal.prevFragment();
Reveal.nextFragment();

// Toggle presentation states, optionally pass true/false to force on/off
Reveal.toggleOverview();
Reveal.togglePause();
Reveal.toggleAutoSlide();

// Change a config value at runtime
Reveal.configure({ controls: true });

// Returns the present configuration options
Reveal.getConfig();

// Fetch the current scale of the presentation
Reveal.getScale();

// Retrieves the previous and current slide elements
Reveal.getPreviousSlide();
Reveal.getCurrentSlide();

Reveal.getIndices(); // { h: 0, v: 0 } }
Reveal.getProgress(); // 0-1
Reveal.getTotalSlides();

// State checks
Reveal.isFirstSlide();
Reveal.isLastSlide();
Reveal.isOverview();
Reveal.isPaused();
Reveal.isAutoSliding();
```

### Slide Changed Event

A 'slidechanged' event is fired each time the slide is changed (regardless of state). The event object holds the index values of the current slide as well as a reference to the previous and current slide HTML nodes.