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.
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 [https://slides.com](https://slides.com?ref=github).
The **basic setup** is for authoring presentations only. The **full setup** gives you access to all reveal.js features and plugins such as speaker notes as well as the development tasks needed to make changes to the source.
### Basic setup
The core of reveal.js is very easy to install. You'll simply need to download a copy of this repository and open the index.html file directly in your browser.
1. Download the latest version of reveal.js from <https://github.com/hakimel/reveal.js/releases>
2. Unzip and replace the example contents in index.html with your own
3. Open index.html in a browser to view it
### Full setup
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.
The presentation markup hierarchy needs to be `.reveal > .slides > section` where the `section` represents one slide and can be repeated indefinitely. If you place multiple `section` elements 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 will be included in the horizontal sequence. For example:
If you want to run multiple presentations side-by-side on the same page you can create instances of the Reveal class. Note that you will also need to set the `embedded` config option to true.
We provide two JavaScript bundles; `/dist/reveal.es5.js` with support for legacy browers and `/dist/reveal.js` which targets modern browsers with ES6 support.
Here's how to import and initialize the ES module version of reveal.js, including the Markdown plugin:
```html
<scripttype="module">
import Reveal from '/dist/reveal.js';
import markdown from '/plugin/markdown/markdown.js';
At the end of your page you need to initialize reveal by running the following code. Note that all configuration values are optional and will default to the values specified below.
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.
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:
You can also include dependencies which are bundled/already present on the page. To include a bundled plugin. replace the `src` property with a reference to a `plugin` instance:
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()`.
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:
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:
To override the method used for navigation when auto-sliding, you can specify the `autoSlideMethod` setting. To only navigate along the top layer and ignore vertical slides, set this to `Reveal.navigateRight`.
reveal.js can automatically animate elements across slides. All you need to do is add `data-auto-animate` to two adjacent slide `<section>` elements and Auto-Animate will animate all matching elements between the two.
Here's a simple example to give you a better idea of how it can be used. The resulting animation will be the word "Magic" sliding 100px downwards.
This example uses the `top` property to move the element but internally reveal.js will use a CSS transform to ensure smooth movement. This same approach to animation works with most animatable CSS properties meaning you can transition things like `position`, `font-size`, `line-height`, `color`, `background-color` and `padding`.
When you navigate between two auto-animated slides we'll do our best to automatically find matching elements between the two slides. For text, we consider it a match if both the text contents and node type are identical. For images, videos and iframes we compare the `src` attribute. We also take into account the order in which the element appears in the DOM.
In situations where automatic matching is not feasible you can give the objects that you want to animate between a matching `data-id` attribute. We prioritize matching `data-id` values above our automatic matching.
Here's an example where we've given both blocks a matching ID since automatic matching has no content to go on.
You can override specific animation settings such as easing and duration either for the whole presentation, per-slide or individually for each animated element. The following configuration attributes can be used to change the settings for a specific slide or element:
| data-auto-animate-easing | ease | A CSS [easing function](https://developer.mozilla.org/en-US/docs/Web/CSS/easing-function).
| data-auto-animate-unmatched | true | Determines whether elements with no matching auto-animate target should fade in. Set to false to make them appear instantly.
| data-auto-animate-duration | 1.0 | Animation duration in seconds.
| data-auto-animate-delay | 0 | Animation delay in seconds (can only be set for specific elements, not at the slide level).
We add state attributes to the different elements involved in an auto-animation. These attributes can be tied into if you want to, for example, fine-tune the animation behavior with custom CSS.
Right before an auto-animation starts we add `data-auto-animate="pending"` to the slide `<section>`. At this point the upcoming slide is visible and all of the animated elements have been moved to their starting positions. Next we switch to `data-auto-animate="running"` to indicate when the elements start animating towards their final properties.
Each individual element is decorated with a `data-auto-animate-target` attribute. The value of the attribute is a unique ID for this particular animation OR "unmatched" if this element should animate as unmatched content.
Slides can be nested within other slides to create vertical stacks (see [Markup](#markup)). When presenting, you use the left/right arrows to step through the main (horizontal) slides. When you arrive at a vertical stack you can optionally press the up/down arrows to view the vertical slides or skip past them by pressing the right arrow. Here's an example showing a bird's-eye view of what this looks like in action:
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:
| default | Left/right arrow keys step between horizontal slides. Up/down arrow keys step between vertical slides. Space key steps through all slides (both horizontal and vertical). |
| linear | Removes the up/down arrows. Left/right arrows step through all slides (both horizontal and vertical). |
| grid | When this is enabled, stepping left/right from a vertical stack to an adjacent vertical stack will land you at the same vertical index.<br><br>Consider a deck with six slides ordered in two vertical stacks:<br>`1.1` `2.1`<br>`1.2` `2.2`<br>`1.3` `2.3`<br><br>If you're on slide 1.3 and navigate right, you will normally move from 1.3 -> 2.1. With navigationMode set to "grid" the same navigation takes you from 1.3 -> 2.3. |
You can swipe to navigate through a presentation on any touch-enabled device. Horizontal swipes change between horizontal slides, vertical swipes change between vertical slides. If you wish to disable this you can set the `touch` config option to false when initializing reveal.js.
If there's some part of your content that needs to remain accessible to touch events you'll need to highlight this by adding a `data-prevent-swipe` attribute to the element. One common example where this is useful is elements that need to be scrolled.
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.
Note that lazy loaded iframes ignore the `viewDistance` configuration and will only load when their containing slide becomes visible. Iframes are also unloaded as soon as the slide is hidden.
When we lazy load a video or audio element, reveal.js won't start playing that content until the slide becomes visible. However there is no way to control this for an iframe since that could contain any kind of content. That means if we loaded an iframe before the slide is visible on screen it could begin playing media and sound in the background.
Custom key bindings can be added and removed using the following Javascript API. Custom key bindings will override the default keyboard bindings, but will in turn be overridden by the user defined bindings in the ``keyboard`` config option.
```javascript
Reveal.addKeyBinding( binding, callback );
Reveal.removeKeyBinding( keyCode );
```
For example
```javascript
// The binding parameter provides the following properties
// keyCode: the keycode for binding to the callback
// key: the key label to show in the help overlay
// description: the description of the action to show in the help overlay
A `slidechanged` event is fired each time the slide is changed. The event object holds the index values of the current slide as well as a reference to the previous and current slide DOM nodes.
Some libraries, like MathJax (see [#226](https://github.com/hakimel/reveal.js/issues/226#issuecomment-10261609)), get confused by the transforms and display states of slides. Often times, this can be fixed by calling their update or render function from this callback.
The `slidechanged` event fires instantly when the slide changes. If you'd rather invoke your event listener when the slide has finished transitioning and is fully visible, you can use the `slidetransitionend` event. The `slidetransitionend` event includes the same event data as described above.
The presentation's current state can be fetched by using the `getState` method. A state object contains all of the information required to put the presentation back as it was when `getState` was first called. Sort of like a snapshot. It's a simple object that can easily be stringified and persisted or sent over the wire.
If you set `data-state="somestate"` on a slide `<section>`, "somestate" will be applied as a class on the document element when that slide is opened. This allows you to apply broad style changes to the page based on the active slide.
When preparing a presentation it can sometimes be helpful to prepare optional slides that you may or may not have time to show. This is easily done by appending a few slides at the end of the presentation, however this means that the reveal.js progress bar and slide numbering will hint that there are additional slides.
To "hide" those slides from reveal.js' numbering system you can add a `data-visibility` attribute to the slide like so `<section data-visibility="uncounted">`.
Slides are contained within a limited portion of the screen by default to allow them to fit any display and scale uniformly. You can apply full page backgrounds outside of the slide area by adding a `data-background` attribute to your `<section>` elements. Four different types of backgrounds are supported: color, image, video and iframe.
Embeds a web page as a slide background that covers 100% of the reveal.js width and height. The iframe is in the background layer, behind your slides, and as such it's not possible to interact with it by default. To make your background interactive, you can add the `data-background-interactive` attribute.
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.
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.
Make sure that the background size is much bigger than screen size to allow for some scrolling. [View example](http://revealjs.com/?parallaxBackgroundImage=https%3A%2F%2Fs3.amazonaws.com%2Fhakim-static%2Freveal-js%2Freveal-parallax-1.jpg¶llaxBackgroundSize=2100px%20900px).
The global presentation transition is set using the `transition` config value. You can override the global transition for a specific slide by using the `data-transition` attribute:
It's easy to link between slides. The first example below targets the index of another slide whereas the second targets a slide with an ID attribute (`<sectionid="some-slide">`):
You can also add relative navigation links, similar to the built in reveal.js controls, by appending one of the following classes on any element. Note that each element is automatically given an `enabled` class when it's a valid navigation route based on the current slide.
Fragments are used to highlight individual elements on a slide. Every element with the class `fragment` will be stepped through before moving on to the next slide. Here's an example: http://revealjs.com/#/fragments
Multiple fragments can be applied to the same element sequentially by wrapping it, this will fade in the text on the first step and fade it back out on the second.
Some libraries, like MathJax (see #505), get confused by the initially hidden fragment elements. Often times this can be fixed by calling their update or render function from this callback.
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)).
Below is an example with clojure code that will be syntax highlighted. When the `data-trim` attribute is present, surrounding whitespace is automatically removed. HTML will be escaped by default. To avoid this, for example if you are using `<mark>` to call out a line of code, add the `data-noescape` attribute to the `<code>` element.
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:
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.
If you want to enable or disable autoplay globally, for all embedded media, you can use the `autoPlayMedia` configuration option. If you set this to `true` ALL media will autoplay regardless of individual `data-autoplay` attributes. If you initialize with `autoPlayMedia: false` NO media will autoplay.
Note that embedded HTML5 `<video>`/`<audio>` and YouTube/Vimeo iframes are automatically paused when you navigate away from a slide. This can be disabled by decorating your element with a `data-ignore` attribute.
reveal.js automatically pushes two [post messages](https://developer.mozilla.org/en-US/docs/Web/API/Window.postMessage) to embedded iframes. `slide:start` when the slide containing the iframe is made visible and `slide:stop` when it is hidden.
Sometimes it's desirable to have an element, like an image or video, stretch to consume as much space as possible within a given slide. This can be done by adding the `.stretch` class to an element as seen below:
The framework has a built-in postMessage API that can be used when communicating with a presentation inside of another window. Here's an example showing how you'd make a reveal.js instance in the given window proceed to slide 2:
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:
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:
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 `<textarea data-template>` like the example below. You'll also need to add the `plugin/markdown/marked.js` and `plugin/markdown/markdown.js` scripts (in that order) to your HTML file. _Note: both these dependencies are already included in the default `index.html`._
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 Flavored Markdown](https://help.github.com/articles/github-flavored-markdown). Sensitive to indentation (avoid mixing tabs and spaces) and line breaks (avoid consecutive breaks).
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-separator` attribute defines a regular expression for horizontal slides (defaults to `^\r?\n---\r?\n$`, a newline-bounded horizontal rule) and `data-separator-vertical` defines vertical slides (disabled by default). The `data-separator-notes` attribute is a regular expression for specifying the beginning of the current slide's speaker notes (defaults to `notes?:`, so it will match both "note:" and "notes:"). 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). The following example customises all available options:
```html
<sectiondata-markdown="example.md"
data-separator="^\n\n\n"
data-separator-vertical="^\n\n"
data-separator-notes="^Note:"
data-charset="iso-8859-15">
<!--
Note that Windows uses `\r\n` instead of `\n` as its linefeed character.
For a regex that supports all operating systems, use `\r?\n` instead of `\n`.
-->
</section>
```
### Element Attributes
Special syntax (through HTML comments) is available for adding attributes to Markdown elements. This is useful for fragments, amongst other things.
We use [marked](https://github.com/chjj/marked) to parse Markdown. To customise marked's rendering, you can pass in options when [configuring Reveal](#configuration):
Presentations can be exported to PDF via a special print stylesheet. This feature requires that you use [Google Chrome](http://google.com/chrome) or [Chromium](https://www.chromium.org/Home) and to be serving the presentation from a web server.
[Fragments](#fragments) are printed on separate slides by default. Meaning if you have a slide with three fragment steps, it will generate three separate slides where the fragments appear incrementally.
If you prefer printing all fragments in their visible states on the same slide you can set the `pdfSeparateFragments` config option to false.
Export dimensions are inferred from the configured [presentation size](#presentation-size). Slides that are too tall to fit within a single page will expand onto multiple pages. You can limit how many pages a slide may expand onto using the `pdfMaxPagesPerSlide` config option, for example `Reveal.configure({ pdfMaxPagesPerSlide: 1 })` ensures that no slide ever grows to more than one printed page.
1. Open your presentation with `print-pdf` included in the query string i.e. http://localhost:8000/?print-pdf. You can test this with [revealjs.com?print-pdf](http://revealjs.com?print-pdf).
* If you want to include [speaker notes](#speaker-notes) in your export, you can append `showNotes=true` to the query string: http://localhost:8000/?print-pdf&showNotes=true
1. Open the in-browser print dialog (CTRL/CMD+P).
1. Change the **Destination** setting to **Save as PDF**.
If you want to add a theme of your own see the instructions here: [/css/theme/README.md](https://github.com/hakimel/reveal.js/blob/master/css/theme/README.md).
All theme variables are exposed as CSS custom properties in the pseudo-class `:root`. See [the list of exposed variables](https://github.com/hakimel/reveal.js/blob/master/css/theme/template/exposer.scss).
reveal.js comes with a speaker notes plugin which can be used to present per-slide notes in a separate browser window. The notes window also gives you a preview of the next upcoming slide so it may be helpful even if you haven't written any notes. Press the »S« key on your keyboard to open the notes window.
Notes are defined by appending an `<aside>` element to a slide as seen below. You can add the `data-markdown` attribute to the aside element if you prefer writing notes using Markdown.
Oh hey, these are some notes. They'll be hidden in your presentation, but you can see them if you open the speaker notes window (hit »S« on your keyboard).
Notes are only visible to the speaker inside of the speaker view. If you wish to share your notes with others you can initialize reveal.js with the `showNotes` configuration value set to `true`. Notes will appear along the bottom of the presentations.
When `showNotes` is enabled notes are also included when you [export to PDF](https://github.com/hakimel/reveal.js#pdf-export). By default, notes are printed in a box on top of the slide. If you'd rather print them on a separate page, after the slide, set `showNotes: "separate-page"`.
- (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 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).
In some cases it can be desirable to run notes on a separate device from the one you're presenting on. The Node.js-based notes plugin lets you do this using the same note definitions as its client side counterpart. See <https://github.com/reveal/notes-server>.
The multiplex plugin allows your audience to follow the slides of the presentation you are controlling on their own phone, tablet or laptop. As of 4.0.0 this plugin has moved to its own repo at <https://github.com/reveal/multiplex>.
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](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.
Read MathJax's documentation if you need [HTTPS delivery](http://docs.mathjax.org/en/latest/start.html#secure-access-to-the-cdn) or serving of [specific versions](http://docs.mathjax.org/en/latest/configuration.html#loading-mathjax-from-the-cdn) for stability.
If you want to include math inside of a presentation written in Markdown you need to wrap the formula in backticks. This prevents syntax conflicts between LaTeX and Markdown. For example:
Plugins should register themselves with reveal.js by calling `Reveal.registerPlugin( MyPlugin )`. Registered plugins _must_ expose a unique `id` property and can optionally expose an `init` function that reveal.js will call to initialize them.
When reveal.js is booted up via `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:
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' )`.
