Web Accessibility Evaluation Methodologies and Tools

Transcription

1 Web Accessibility Evaluation Methodologies and Tools Jared Smith & Jonathan Whiting webaim.org

2 Accessibility vs. Compliance

3 Accessibility > Compliance

4 Technical Accessibility vs. Functional Accessibility

5 Accessibility is about the human experience. Only humans can adequately evaluate true accessibility.

6 Use a Checklist

7 Use a Checklist WCAG 1.0 Section webaim.org/standards/508/checklist/ WCAG webaim.org/standards/wcag/checklist/ Customized

8 Know the limitations of guidelines Very subject to interpretation Confusing language ( programmatically determinable, Media alternative for text, etc.) Lag behind technology innovation Neglect many users with disabilities (especially cognitive/learning disabilities)

9 Disable styles and linearize tables Web developer toolbar WAVE Disable browser styles Check: reading/navigation order reliance on color, layout, or positioning useful page structure/markup "Readable"? Not very useful for complex web applications

10 Check alternative text Content and Function Is alt text succinct, yet accurate and equivalent? Does alt text makes sense in context? Do all functional elements (linked images, buttons, image maps) have proper alternative text? MANY intricacies to proper alternative text

11 Verify color and contrast Check color contrast: webaim.org/resources/contrastchecker/ Print on a grayscale printer WAVE5 Check color reliance: colorfilter.wickline.org Also check high contrast mode

12 Test Content Scaling Enlarge the text size in your web browser to ~150%. Note that WCAG 2.0 requires 200%. Zoom passes WCAG requirement. Is the page readable and usable? Is horizontal scrolling minimized? Zoom the web page in your browser (enlarge fonts and images). Is text in images readable?

13 Check keyboard accessibility Navigate the site using only the keyboard (Tab, Shift + Tab, Enter, etc.). Is all functionality available? Is a "skip navigation" link available? Does it function correctly? Is it visible on focus? Make sure the navigation order is logical. Is a visible keyboard focus indicator/outline present?

14 Check keyboard accessibility Be careful when default form control behavior is modified (auto-tabbing, jump select menus, etc.) Use buttons and links appropriately. Modal dialogs must be keyboard modal (e.g., maintain focus). Non-modal dialogs should auto-close appropriately. Esc should usually close menus, dialogs, etc.

15 Form validation & error recovery Use standard <label> when possible. ARIA can enhance labelling and descriptions. Are error prevention/recovery mechanisms present and easy-to-use? Is client-side validation relied upon? Methods: Errors at the top. Alert and focus. Inline errors.

16 Check in a screen reader Focus on navigation, forms, document structure, and dynamic content. WebAIM tutorials for JAWS, NVDA, and VoiceOver. Try testing without the mouse or monitor. Don t worry about pronunciation. Sometimes it's the screen reader's fault.

17 Valid HTML & CSS Valid code supports accessibility. WCAG 2.0 only requires that significant validation issues be avoided. HTML Validator - CSS Validator -

18 User Testing Is accessibility testing with users vital? Be careful with inaccessible content. Conduct basic user testing with users with disabilities. Focus on the entire experience while identifying instances of inaccessibility. Rocket Surgery and Accessibility User Testing -

19 Automated Tools There are too many to list. Auditing tools are best utilized in the remediation process or to detect issues after accessibility has been implemented. Tools cannot replace good education.

20 wave.webaim.org

21 Review Use a checklist Disable styles and linearize tables Check alternative text Verify color and contrast Test content scaling Check keyboard accessibility Evaluate form accessibility and usability Test with a screen reader Valid HTML and CSS User testing Automated testing

22 Documenting Issues Structuring reports: By page By guidelines/error type By severity Provide a user severity ranking (WCAG levels don t work). Implementation impact can also be valuable. Must, Should, and May. Go beyond accessibility guidelines.