Usability and accessibility on the web
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Usability and accessibility on the web

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Usability and accessibility on the web Usability and accessibility on the web Presentation Transcript

  • Usability and Accessibility on the Web
  • Usability
    • Usability is the study of the ease with which people can employ a particular tool or other human-made object in order to achieve a particular goal.
    • A web application must function and it must be usable
    • There are a lot of books on the subject - we only have time to present some best practices
  • Navigation on the web site
    • Search + Browsing
    • Classify the content
    • The user must know where he is inside the web site  
    • The user mus know how he arrived in the page
    • Navigation in the content and in the options of the site
  • Conventions used for navigation Where am I How we got here Site logo “ utilities” sections Simple search + instructions + options
  • Home page
    • Logo + tag line
    • Sections/classification
    • Search 
    • Teasing
    • Dynamic content
    • [publicite]
    • Shortcuts to the most visited pages
    • [sign-up]
  • Home page objectives
    • Show what the user is looking for
    • Offer alternatives (something more than the user is looking for)  
    • Show how to begin and use the web site
    • Show credibility and trust
  • logo tagline search navigation Dynamic content sections commercials Welcome What it offers teasing
  • What elements can you identify?
  • Accessibility 
    • Web Content Accessibility Guidelines (WCAG) 2.0 how the web content is made accessible to people with handicaps. 
    • Accessibility should take into account a large number of handicaps: visual, auditives, physical, neurological, mental.
    • => this should make the web content more usable for older people and for people in general
  • Introduction
    • 160 million people have some kind of visual handicap
    • Around 40 million people are blind
    • There are tools that allow blind people to use the web
    • There are people who have different handicaps that use other types of tools
  • Guides for accessible web sites
    • Web Accessibility Initiative –  Workgroup W3C for improving the web accessibility.
    • Web Content Accessibility Guidelines 1.0 – 1999 
    • Web Content Accessibility Guidelines 2 .0 – 2008 
    • The instructions are grouped by their characteristics and by their priority (1 or A being the most important)
  • Objective no 1: the information and the elements of the interface must be perceived
    • All the non-text content must have an alternative text.  
      • For an image we can specify an alternative text to describe the content of the image (<img alt=&quot;description&quot;> ..) 
      • If a sound has a specific significance (i.e. it announces an error) it must be accompanied by an explaining text
      • The multimedia objects need to have texts to explain the content
  • Examples
    • Image with an associated explanation
    • Video with explanations
  • Objective no 1: the information and the elements of the interface must be perceived
    • The content of the page must maintain their importance when the presentation method changes
    • Understand the relations between the graphic elements
    • Insure that the text in the page is read in the correct order  
    • The instructions on how a page must work mustn’t be done only by graphic symbols.  
      • ex: the arrows that mark the next page must be explained with text.  
  • Examples
    • The * doesn’t mean for everybody that the fields are mandatory
    • <img src=&quot;../graphics/fback.gif&quot; alt=&quot;Previous chapter&quot; border=&quot;0&quot;>
    • Use « tabindex » to specify the order in which the elements must be read
  •  
  • Objective no 1: the information and the elements of the interface must be perceived
    • The content must be easy to perceive by separating the foreground and the background 
      • The color mustn’t be the only way in which information is provided
      • There must be a way to stop the background sound of a page
  • Examples
    • test to identify the color perception 
    • Explain how colors are used for error messages
  • Objective no. 2 - the components of the interface should be operable 
    • All the functionalities should be accessible from the keyboard
    • If for the navigation are used non-standard features (other than tab and arrows) the user must be warned about them
    • The user should have enough time to read the content of the page
    • In a web page we shouldn’t have flashes as they can cause convulsions ( see . http://www.w3.org/TR/2007/WD-WCAG20-20071211/#general-thresholddef )
  • Examples
    • You can produce flashes by using the <blink> tag or through gif or flash files.
    • Flash menus usually can’t be controlled by keyboard
    • Some e-banking websites allow very short working sessions therefore not allowing sufficient time to read all the information
  • Objective no. 2 - the components of the interface should be operable
    • The users should be allowed to skip the sections that are repeating in every page 
    • The pages should have explicite titles
    • The components of the interface should gain focus in a logical order
  • Examples
    • How to avoid a repeating component
    • Explicit titles Mention the section of the site
      • Don’t use the same title for all the pages 
    • tabindex allows to specify the navigation order 
  • Objective no. 3 The interface and the content of the page must be understandable 
    • The users must be allowed to avoid or correct errors when using the interface
    • Use labels and/or instructions when you need data from the user
  • Examples
    • Avoid / Correct the errors
      • Good example->
      • Bad example - insufficient information from the beginning 
    • Use labels and instructions. Tell which is the expected format for the input data 
  • Conclusions
    • The page doesn’t need only to function correctly
      • It has to be usable
      • It has to be accessible
    • Think who is most likely to use your website
    • Know the existing standards and recommendations
  • References
    • Web Content Accessibility Guidelines 2.0 – W3C working draft
    • Accessible Web Design Examples
    • Web Content Accessibility Guidelines 1.0
    • See the links inside the presentation
  • About the exam
    • 75 minutes
    • 1 A4 cheat sheet that can contain only descriptions of HTML or CSS elements or of Javascript objects
    • You are not allowed to have code examples on the cheat sheet
    • You are not allowed to exchange cheat-sheets with your colleagues during the exam
  • About the exam
    • If your cheat sheet doesn’t follow these rules it will be confiscated 
    • The exam will consist in
      • 3-5 theoretical questions (max 5 lines for each answer)
      • Practical questions
        • Implement a feature as seen in an image
        • Validate a form input with javascript
        • Tell how an element will be displayed having the code available
  • About the exam
    • The exam does not repeat this session
    • If you fail you will have to take it again in september
    • Any attempt of cheating will be severely punished (automatically failing the subject+ proposal of expulsion from the faculty)
    • In order to pass you need to score at least 50% of the exam points