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Accessible UIs with jQuery and Infusion


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Overview of accessible Web development techniques with jQuery and Fluid's Infusion application framework. This talk gives developers a primer in DHTML accessibility techniques such as keyboard navigation and ARIA, while teaching them the strengths of Infusion for building large applications in JavaScript.

Presented at 2009 Ajax Experience, Boston.

Published in: Technology
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Accessible UIs with jQuery and Infusion

  1. 1. Building Accessible User Interfaces with jQuery and Fluid Infusion Colin Clark, Fluid Project Technical Lead, Adaptive Technology Resource Centre
  2. 2. Topics We’ll Cover • The Fluid community • Introducing Infusion • Developing accessible JavaScript • Infusion’s Architecture • Techniques for portals, mashups, CMS’s • Where we’re headed
  3. 3. Fluid... • Is an open source community of • Designers • Developers • Accessibility experts • Helps other open communities • Consists of universities, museums and individuals
  4. 4. What We Do • Offer design advice and resources • Contribute to other communities: • jQuery UI • Dojo • W3C Accessibility • Build Infusion, our JavaScript application framework
  5. 5. Introducing
  6. 6. World, Meet Infusion • Application framework built on top of jQuery • The culmination of our work helping others • Designed for usability and accessibility • Open architecture: everything is configurable
  7. 7. What’s in Infusion? • A development framework for building apps • UI components you can reuse and adapt • Lightweight CSS framework for styling • Accessibility tools and plugins for jQuery
  8. 8. Building Great UIs Is Hard • Your code gets unruly as it grows • UIs are hard to reuse or repurpose • Design change requires big code change • Accessibility is confusing • Combining different code/libraries doesn’t always work
  9. 9. Flexible User Interfaces Infusion is an application framework designed to provide unprecedented flexibility while preserving interoperability.
  10. 10. Types of JavaScript Tools • Foundational Toolkits • Application Frameworks ... compare and contrast
  11. 11. Foundational toolkits • Totally presentation focused • DOM manipulation • Event binding jQuery • Ajax Prototype Dojo core
  12. 12. Application frameworks • Model notifications “something changed here” • Views to help keep your presentational code clean • Data binding to sync the display with your model SproutCore Dojo/Dijit/ Dojox Cappuccino
  13. 13. Infusion is Different • Accessibility baked right in • Carefully designed interactions • Markup is in your control • Not the same old MVC • Supports portals, mashups and CMS’s
  14. 14. Deeply Accessible
  15. 15. What is Accessibility?
  16. 16. A New Definition • Accessibility is the ability of the system to accommodate the needs of the user • Disability is the mismatch between the user and the interface provided • We all experience disability • Accessible software = better software
  17. 17. Assistive Technologies • Present and control the user interface in different ways • Not just screen readers! • Use built-in operating system APIs to understand the user interface Screen readers Screen magnifiers On-screen keyboards
  18. 18. DHTML: A New Can of Worms • Shift from documents to applications • Familiar a11y techniques aren’t enough • Most DHTML is completely inaccessible • New techniques are still being figured out
  19. 19. The Problem • Custom widgets often look, but don’t act, like their counterparts on the desktop • HTML provides only simple semantics • Not enough information for ATs • Dynamic updates require new design strategies to be accessible
  20. 20. The Solution • Describe user interfaces with ARIA • Add consistent keyboard controls • Provide flexible styling and presentation
  21. 21. Supporting Assistive Technology
  22. 22. Opaque Markup // These are tabs. How would you know? <ol> <li><a href=”#cats”>Cats</a></li> <li><a href=”#dogs”>Dogs</a></li> <li><a href=”#gators”>Gators</a></li> </ol> <div> <div id=”cats”>Cats meow.</div> <div id=”dogs”>Dogs bark.</div> <div id=”gators”>Gators bite.</div> </div>
  23. 23. Opaque Markup: Tabs
  24. 24. ARIA • Accessible Rich Internet Applications • W3C specification in the works • Fills the semantic gaps in HTML • Roles, states, and properties • Live regions
  25. 25. Roles, States, Properties • Roles describe widgets not present in HTML 4 • slider, menubar, tab, dialog • Properties describe characteristics: • draggable, hasPopup, required • States describe what’s happening: • busy, disabled, selected, hidden
  26. 26. Using ARIA // Now *these* are Tabs! <ol id=”animalTabs” role=”tablist” tabindex=”0”> <!-- Individual Tabs shouldn’t be focusable --> <!-- We’ll focus them with JavaScript instead --> <li role=”tab”><a href=”#” tabindex=”-1”>Cats</a></li> <li role=”tab”><a href=”#” tabindex=”-1”>Dogs</a></li> <li role=”tab”><a href=”#” tabindex=”-1”>Gators</a></li> </ol> <div id=”panels”> <div role=”tabpanel” aria-labelledby=”cats”>Cats meow.</div> <div role=”tabpanel” aria-labelledby=”dogs”>Dogs bark.</div> <div role=”tabpanel” aria-labelledby=”gators”>Gators bite.</div> </div>
  27. 27. Adding ARIA in Code // Identify the container as a list of tabs. tabContainer.attr("role", "tablist"); // Give each tab the "tab" role. tabs.attr("role", "tab"); // Give each panel the appropriate role, panels.attr("role", "tabpanel"); panels.each(function (idx, panel) { var tabForPanel = that.tabs.eq(idx); // Relate the panel to the tab that labels it. $(panel).attr("aria-labelledby", tabForPanel[0].id); });
  28. 28. Keyboard Accessibility
  29. 29. Keyboard Navigation • Everything that works with the mouse should work with the keyboard • ... but not always in the same way • Support familiar conventions
  30. 30. Keyboard Conventions • Tab key focuses the control or widget • Arrow keys select an item • Enter or Spacebar activate an item • Tab is handled by the browser. For the rest, you need to write code. A lot of code.
  31. 31. Keyboard a11y: Tabs
  32. 32. Tabindex examples <!-- Tab container should be focusable --> <ol id=”animalTabs” tabindex=”0”> <!-- Individual Tabs shouldn’t be focusable --> <!-- We’ll focus them with JavaScript instead --> <li id=”tab1”> <a href=”#cats” tabindex=”-1”>Cats</a> </li> <li id=”tab2”> <a href=”#cats” tabindex=”-1”>Dogs</a> </li> <li id=”tab3”> <a href=”#cats” tabindex=”-1”>Alligators</a> </li> </ol>
  33. 33. Making Things Tabbable • Tabindex varies subtly across browsers • jquery.attr() normalizes it as of 1.3 • For all the gory details: getting-setting-and-removing-tabindex-values-with- javascript/ // Make the tablist accessible with the Tab key. tabContainer.attr("tabindex", "0"); // And take the anchors out of the Tab order. $(“a”, tabs).attr("tabindex", "-1");
  34. 34. Adding the Arrow Keys // Make each tab accessible with the left and right arrow keys. tabContainer.fluid("selectable", { selectableSelector: that.options.selectors.tabs, direction: fluid.a11y.orientation.HORIZONTAL, onSelect: function (tab) { $(tab).addClass(that.options.styles.highlighted); }, onUnselect: function (tab) { $(tab).removeClass(that.options.styles.highlighted); } });
  35. 35. Making Them Activatable // Make each tab activatable with Spacebar and Enter. tabs.fluid("activatable", function (evt) { // Your handler code here. Maybe the same as .click()? });
  36. 36. Documentation • Tutorial: +Tutorial • API Reference: +Plugin+API
  37. 37. Infusion Goes Deeper • jQuery Keyboard Navigation Plugin • ARIA everywhere • Everything is highly adaptable and flexible • UI Options and the Fluid Skinning System: • Users can customize their environment
  38. 38. UI Options • One size doesn’t fit all • Allows users to customize your app: • layout • styling • navigation • Uses FSS by default; can be configured to work with your own classes
  39. 39. UI Options & FSS
  40. 40. UI Options & FSS
  41. 41. CSS Frameworks “If you’re going to use a framework, it should be yours; one that you’ve created. You can look at existing frameworks for ideas and hack at it. But the professionals in this room are not well served by picking up a framework and using it as-is.” - Eric Meyer
  42. 42. Fluid Skinning System • FSS is built to be hacked on • Provides a core set of building blocks • Reset, text, layouts, themes • Namespaced: no conflicts with your stuff • Themes for better legibility & readability
  43. 43. Open Architecture
  44. 44. Markup Agnosticism • HTML is so fundamental to Web UIs • Others lock away markup in a black box • Markup should be totally free to edit, adapt, or replace • Libraries shouldn’t bake in assumptions about your markup • Unobtrusiveness everywhere
  45. 45. Handling Markup: Dojo <div class="dijitDialog" tabindex="-1" waiRole="dialog" waiState="labelledby- ${id}_title"> <div dojoAttachPoint="titleBar" class="dijitDialogTitleBar"> <span dojoAttachPoint="titleNode" class="dijitDialogTitle" id="$ {id}_title"></span> <span dojoAttachPoint="closeButtonNode" class="dijitDialogCloseIcon" dojoAttachEvent="onclick: onCancel, onmouseenter: _onCloseEnter, onmouseleave: _onCloseLeave" title="${buttonCancel}"> <span dojoAttachPoint="closeText" class="closeText" title="$ {buttonCancel}">x</span> </span> </div> <div dojoAttachPoint="containerNode" class="dijitDialogPaneContent"></div> </div>
  46. 46. Handling Markup: jQuery UI
  47. 47. Handling Markup: Infusion fluid.defaults("fluid.fileQueueView", { selectors: { fileRows: ".flc-uploader-file", fileName: ".flc-uploader-file-name", fileSize: ".flc-uploader-file-size", fileIconBtn: ".flc-uploader-file-action", errorText: ".flc-uploader-file-error" },
  48. 48. Components “Components suck. Apps built with components look like it” • Infusion components aren’t black boxes • Fundamentally adaptable: • Change the markup • Restyle with CSS • Add/replace actual behaviour • Everything is super-loosely coupled
  49. 49. Component Families: Reorderer lists images layouts Infusion components come in families
  50. 50. More Components Uploader Inline Edit Pager
  51. 51. Model, View... but not Controller • MVC is a given in most framework • JavaScript’s functional idioms offer alternatives (hint: events) • Infusion has no controller layer at all • ... and none of the classical inheritance cruft that usually goes with it
  52. 52. Traditional MVC Model n atio oti c State Query State Change ge N n Cha View Selection View Controller User Gestures
  53. 53. The Problem with Controllers • Controllers are the least defined • What’s “glue?” • Always referred to as the non-reusable part • MVC has been warped over the decades • The framework should take care of the glue
  54. 54. Infusion Models & Views Model • Controller is replaced by events Change Noti cation • Reads to the model are transparent • State changes and notification are just events State Query State Change • Transparent architecture: you can use View the same events we use Framework
  55. 55. Plain Old Models • M is the most important thing in your app • Data needs to travel seamlessly between client and server • Most toolkits force a model to extend some base class or particular structure In Infusion, models are just plain old JSON
  56. 56. Playing Nice With Others
  57. 57. Portals, Mashups, and CMS’s • These days, diverse code and markup coexists • Most JavaScript is written as if it owns the whole browser • As you combine stuff, things can break • Namespacing and privacy is essential
  58. 58. Writing Collision-Free JavaScript • Put code in a unique namespace • Use closures for privacy • Support more than one on the page • Scope all variables to an instance • Avoid hard-baking ID selectors • Constrain selectors within a specific element
  59. 59. Keeping it to Ourselves • Infusion takes namespacing seriously • We won’t steal your names • Components are carefully scoped • We won’t accidently grab the wrong stuff • Infusion doesn’t expect control of the page
  60. 60. Tying it All Together • Infusion helps you with accessibility • Components you can really work with • Simple structure so your code can grow • Totally transparent, event-driven design • Markup and models are under your control • No inheritance or controller cruft
  61. 61. Where We’re Going
  62. 62. Infusion Next Steps • Infusion 1.2 coming in October: • New lightweight Inversion of Control • Data Grid and reworked Pager components • Lots of bug fixes • New demos portal with example code • Screencasts
  63. 63. Fluid Engage • Open source collaboration with museums • Visitor engagement: learn and contribute • Use phones visitors bring into the museum • Mobile apps and in-gallery kiosks • All built with open source Web technology
  64. 64. Our Mobile Approach • No hard intrusions on your content • Don’t subvert good Web idioms • Your choice: native-like or webbish
  65. 65. Infusion Mobile • mFSS: themes for iPhone, Android, more • ScreenNavigator: unobtrusive mobile navigation • Components designed for the mobile Web
  66. 66. Kettle: Server-side JS • Built on top of the JSGI server spec • Don’t need lots of new APIs on server • Envjs provides a full browser • Infusion as application framework • Choose where markup gets rendered • Natural, familiardesigners for Web developers and environment
  67. 67. Wrapping Up • Tools for everyone: • ARIA • Dojo • jQuery • Infusion • Give Infusion a try and let us know • We’re a friendly community!
  68. 68. Wrapping Up Please fill out an evaluation.
  69. 69. Questions?