Accessible Web Mapping Apps
## What is accessibility
Make content usable for everyone regardless of abilities.
Wide range of disabilities
## Why is accessibility important?
- The ADA and Section 508
- People with different abilities should have equal access
- Good accessibility is good user experience
## WCAG
Web Content Accessibility Guidelines
## What we will cover today
- Focus and keyboard accessibility
- Color and color contrast
- Text alternatives
- Map for non-sighted users
- Test for accessibility
Focus and keyboard accessibility
- WCAG 2.4.7:
Interactive elements should have clear focus.
- WCAG
1.3.2: Navigation (tab) order should be logical and intuitive.
- WCAG
2.1.1: Keyboard users should be able to use functionalities using keyboard only.
- WCAG
2.1.2: Content does not "trap" keyboard focus within subsections.
## Test focus and tab order
- Tab through page to verify all interactive elements have focus
- Focus order matches intended reading order
- Interact with all links and controls using only keyboard
- No keyboard trap except for modals
- Off-screen/invisible content should not receive focus
Color and color contrast
- WCAG 1.4.1:
Color is not the only visual means of conveying information.
- WCAG 1.4.3: Text
needs to have contrast ratio of at least 4.5:1.
Color ramp
Use Color Brewer to select colorblind safe colors
White text on colored background
Flipping the contrast
## Test color and color contrast
- Look for content differentiated by color only
- Use a [contrast ratio calculator](https://contrast-ratio.com/)
- Review color contrast issues reported by automated test tool
([aXe](https://chrome.google.com/webstore/detail/axe/lhdoppojpmngadmnindnejefpokejbdd))
## Text alternatives
[WCAG 1.1.1](https://www.w3.org/TR/UNDERSTANDING-WCAG20/text-equiv-all.html): Non-text content has text
alternative.
If an image conveys meaning, write effective alternate text.
If an image is decorative, use alt=""
.
## Write effective alternate text
- Think about how users will be doing with the information
- Be accurate in presenting the content in images
- Be succinct
- No need to use the phrase "image of ..." to describe images
## Map for non-sighted users
Display a text description of the map
"The Esri Olympia regional office is located at 111 Market St NE Suite 250 across
the street from the Farmer's Market."
Provide data in an alternate format
## Test for accessibility
1. Automated test
2. Keyboard test
3. Screen reader test
4. Color test
Automated test with aXe
- Tests rendered page in browser
- Less false positives
- Accessible
Keyboard test
Key |
Action |
Tab, Shift + Tab |
Move keyboard focus |
Enter |
Click links |
Enter, Space |
Click buttons |
Arrow keys |
Move within menus, tabs, radio buttons |
Screen reader
OS |
Screen reader |
Browser |
MacOS |
VoiceOver |
Safari |
Windows |
NVDA |
Firefox |
Windows |
JAWS |
IE/Edge |
## Screen reader basics
- [A11ycasts: VoiceOver](https://youtu.be/5R-6WvAihms)
- [A11ycasts: NVDA](https://youtu.be/Jao3s_CwdRU)
## Color test
- Automated color contrast test results may need manual verification
- Look for information differentiated only by color
## What we covered today
- Focus and keyboard accessibility
- Color and color contrast
- Text alternatives
- Map for non-sighted users
- Test for accessibility
## Additional resources
- [MDN: Accessibility](https://developer.mozilla.org/en-US/docs/Web/Accessibility)
- [Google Developers Web Fundamentals:
Accessibility](https://developers.google.com/web/fundamentals/accessibility/)
- [The A11Y Project](https://a11yproject.com/)
- [GeoNet: Accessibility](https://community.esri.com/groups/accessibility)
## Questions?
Link to slides: [https://arcg.is/1jGXS5](https://arcg.is/1jGXS5)