Enhancements to impress.js web based presentation code

Clone this repo:


  1. 5b6042d impress.js: make past, present and future classes work with non-linear steps by James Bottomley · 10 years ago master
  2. 46f041b impress.js: Add relative transformations. by James Bottomley · 10 years ago
  3. 80e759c impress.js: add build transitions by James Bottomley · 10 years ago
  4. d505df4 Merge pull request #364 from reiz/master by Bartek Szopka · 10 years ago
  5. 2801ed3 Remove comma from bower.json to make it valid JSON by reiz · 10 years ago


It's a presentation framework based on the power of CSS3 transforms and transitions in modern browsers and inspired by the idea behind prezi.com.


impress.js may not help you if you have nothing interesting to say ;)


Use the source, Luke ;)

If you have no idea what I mean by that, or you just clicked that link above and got very confused by all these strange characters that got displayed on your screen, it's a sign, that impress.js is not for you.


Fortunately there are some guys on GitHub that got quite excited with the idea of building editing tool for impress.js. Let's hope they will manage to do it.


Official demo

impress.js demo by @bartaz

Examples and demos

More examples and demos can be found on Examples and demos wiki page.

Feel free to add your own example presentations (or websites) there.

Other tutorials and learning resources

If you want to learn even more there is a list of tutorials and other learning resources on the wiki, too.

There is also a book available about Building impressive presentations with impress.js by Rakhitha Nimesh Ratnayake.


If you've found a bug or have a great idea for new feature let me know by [adding your suggestion] (http://github.com/bartaz/impress.js/issues/new) to issues list.

If you have fixed a bug or implemented a feature that you'd like to share, send your pull request against [dev branch] (http://github.com/bartaz/impress.js/tree/dev). But remember that I only accept code that fits my vision of impress.js and my coding standards - so make sure you are open for discussion :)


impress.js name in courtesy of @skuzniak.

It's an (un)fortunate coincidence that a Open/LibreOffice presentation tool is called Impress ;)


0.5.3 (browse, zip, tar)


Version 0.5 introduced events including impress:stepenter, but this event was not triggered properly in some specific transition types (for example when only scale was changing between steps). It was caused by the fact that in such cases expected transitionend event was not triggered.

This version fixes this issue. Unfortunately modern transitionend event is no longer used to detect when the transition has finished, but old school (and more reliable) setTimeout is used.

0.5.2 (browse, zip, tar)


More descriptive comments added to demo CSS and impress.js source file, so now not only index.html is worth reading ;)

0.5.1 (browse, zip, tar)


Changes in version 0.5 introduced a bug (#126) that was preventing clicks on links (or any clickable elements) on currently active step. This release fixes this issue.

0.5 (browse, zip, tar)


  • API changed, so that impress() function no longer automatically initialize presentation; new method called init was added to API and it should be used to start the presentation
  • event impress:init is triggered on root presentation element (#impress by default) when presentation is initialized
  • new CSS classes were added: impress-disabled is added to body element by the impress.js script and it's changed to impress-enabled when init() function is called
  • events added when step is entered and left - custom impress:stepenter and impress:stepleave events are triggered on step elements and can be handled like any other DOM events (with addEventListener)
  • additional past, present and future classes are added to step elements
    • future class appears on steps that were not yet visited
    • present class appears on currently visible step - it's different from active class as present class is added when transition finishes (step is entered)
    • past class is added to already visited steps (when the step is left)
  • and good news, goto() API method is back! it seems that goto was a future reserved word but isn't anymore, so we can use this short and pretty name instead of camelCassy stepTo - and yes, that means API changed again...
  • additionally goto() method now supports new types of parameters:
    • you can give it a number of step you want to go to: impress().goto(7)
    • or its id: impress().goto("the-best-slide-ever")
    • of course DOM element is still acceptable: impress().goto( document.getElementById("overview") )
  • and if it's not enough, goto() also accepts second parameter to define the transition duration in ms, for example impress().goto("make-it-quick", 300) or impress().goto("now", 0)


In current version calling impress() doesn't automatically initialize the presentation. You need to call init() function from the API. So in a place were you called impress() to initialize impress.js simply change this call to impress().init().

Version 0.4 changed goto API method into stepTo. It turned out that goto is not a reserved word anymore, so it can be used in JavaScript. That's why version 0.5 brings it back and removes stepTo.

So if you have been using version 0.4 and have any reference to stepTo API method make sure to change it to goto.

0.4.1 (browse, zip, tar)


Changes is version 0.4 introduced a bug causing JavaScript errors being thrown all over the place in fallback mode. This release fixes this issue.

It also adds a flag impress.supported that can be used in JavaScript to check if impress.js is supported in the browser.

0.4 (browse, zip, tar)


  • configuration options on #impress element: data-perspective (in px, defaults so 1000), data-transition-duration (in ms, defaults to 1000)
  • automatic scaling to fit window size, with configuration options: data-width (in px, defaults to 1024), data-height (in px, defaults to 768), max-scale (defaults to 1), min-scale (defaults to 0)
  • goto API function was renamed to stepTo because goto is a future reserved work in JavaScript, so please make sure to update your code
  • fallback impress-not-supported class is now set on body element instead of #impress element and it's replaced with impress-supported when browser supports all required features
  • classes step-ID used to indicate progress of the presentation are now renamed to impress-on-ID and are set on body element, so please make sure to update your code
  • basic validation of configuration options
  • couple of typos and bugs fixed
  • favicon added ;)


If in your custom JavaScript code you were using goto() function from impress.js API make sure to change it to stepTo().

If in your CSS you were using classes based on currently active step with step- prefix, such as step-bored (where bored is the id of the step element) make sure to change it to impress-on- prefix (for example impress-on-bored). Also in previous versions these classes were assigned to #impress element and now they are added to body element, so if your CSS code depends on this, it also should be updated.

Same happened to impress-not-supported class name - it was moved from #impress element to body, so update your CSS if it's needed.


Changes and fixes added in this version have broken the experience on Blackberry Playbook with OS in version 1.0. It happened due to a bug in the Playbook browser in this version. Fortunately in version 2.0 of Playbook OS this bug was fixed and impress.js works fine.

So currently impress.js work only on Blackberry Playbook with latest OS. Fortunately, it seems that most of the users [are quite quick with updating their devices] (http://twitter.com/brcewane/status/178230406196379648)

0.3 (browse, zip, tar)


  • minor CSS 3D fixes
  • basic API to control the presentation flow from JavaScript
  • touch event support
  • basic support for iPad (iOS 5 and iOS 4 with polyfills) and Blackberry Playbook


Because API was introduced the way impress.js script is initialized was changed a bit. You not only has to include impress.js script file, but also call impress() function.

See the source of index.html for example and more details.

0.2 (browse, zip, tar)

  • tutorial/documentation added to index.html source file
  • being even more strict with strict mode
  • code clean-up
  • couple of small bug-fixes

0.1 (browse, zip, tar)

First release.

Contains basic functionality for step placement and transitions between them with simple fallback for non-supporting browsers.



Currently impress.js works fine in latest Chrome/Chromium browser, Safari 5.1 and Firefox 10. With addition of some HTML5 polyfills (see below for details) it should work in Internet Explorer 10 (currently available as Developers Preview). It doesn‘t work in Opera, as it doesn’t support CSS 3D transforms.

As a presentation tool it was not developed with mobile browsers in mind, but some tablets are good enough to run it, so it should work quite well on iPad (iOS 5, or iOS 4 with HTML5 polyfills) and Blackberry Playbook.

Still interested?

Additionally for the animations to run smoothly it's required to have hardware acceleration support in your browser. This depends on the browser, your operating system and even kind of graphic hardware you have in your machine.

For browsers not supporting CSS3 3D transforms impress.js adds impress-not-supported class on #impress element, so fallback styles can be applied to make all the content accessible.

Even more explanation and technical stuff

Let‘s put this straight -- wide browser support was (and is) not on top of my priority list for impress.js. It’s built on top of fresh technologies that just start to appear in the browsers and I'd like to rather look forward and develop for the future than being slowed down by the past.

But it's not “hard-coded” for any particular browser or engine. If any browser in future will support features required to run impress.js, it will just begin to work there without changes in the code.

From technical point of view all the positioning of presentation elements in 3D requires CSS 3D transforms support. Transitions between presentation steps are based on CSS transitions. So these two features are required by impress.js to display presentation correctly.

Unfortunately the support for CSS 3D transforms and transitions is not enough for animations to run smoothly. If the browser doesn't support hardware acceleration or the graphic card is not good enough the transitions will be laggy.

Additionally the code of impress.js relies on APIs proposed in HTML5 specification, including classList and dataset APIs. If they are not available in the browser, impress.js will not work.

Fortunately, as these are JavaScript APIs there are polyfill libraries that patch older browsers with these APIs.

For example IE10 is said to support CSS 3D transforms and transitions, but it doesn't have classList nor dataset APIs implemented at the moment. So including polyfill libraries should help IE10 with running impress.js.

And few more details about mobile support

Mobile browsers are currently not supported. Even Android browsers that support CSS 3D transforms are forced into fallback view at this point.

Fortunately some tablets seem to have good enough hardware support and browsers to handle it. Currently impress.js presentations should work on iPad and Blackberry Playbook.

In theory iPhone should also be able to run it (as it runs the same software as iPad), but I haven't found a good way to handle its small screen.

Also note that iOS supports classList and dataset APIs starting with version 5, so iOS 4.X and older requires polyfills to work.


Copyright 2011-2012 Bartek Szopka

Released under the MIT and GPL (version 2 or later) Licenses.