Accessibility engineering

Overview

Accessibility is not a checklist — it is a commitment to not excluding users. 1 in 4 adults has some form of disability. Inaccessible software is defective software. This skill bakes accessibility in during development, not as a retrofit.

When to Use

• Before implementing any UI component
• Before any UI is marked complete
• As part of the /review workflow for frontend changes

Process

Step 1: Semantic HTML first

Use the right HTML elements before reaching for ARIA:

• Buttons for actions (<button>), links for navigation (<a href>)
• Headings for document structure (<h1>–<h6> in correct order)
• Lists for lists (<ul>, <ol>)
• Form labels associated with inputs (<label for>)
• Landmark regions (<nav>, <main>, <header>, <footer>, <aside>)

ARIA only when native semantics are insufficient.

Step 2: Keyboard navigation

Every interactive element must be:

• Reachable by Tab
• Activatable by Enter/Space
• Part of a logical tab order
• Visually focused (:focus-visible style)
• Not trapped in a dead end (modals must trap focus; must release on close)

Test: complete the key user journeys using only the keyboard.

Step 3: Screen reader testing

Test with at least one screen reader:

• VoiceOver (macOS/iOS) + Safari
• NVDA or JAWS (Windows) + Chrome
• TalkBack (Android)

Verify: can a screen reader user complete the same tasks as a sighted user?

Step 4: Color and contrast

• Text contrast ratio: ≥ 4.5:1 for normal text, ≥ 3:1 for large text (WCAG AA)
• Do not convey information by color alone (use icons, patterns, text)
• Test in grayscale mode

Step 5: Dynamic content

• Announce dynamic updates with aria-live regions
• Focus management after navigation (move focus to new content)
• Loading states must be communicated to screen readers
• Errors must be associated with their form fields

Step 6: Images and media

• All meaningful images have descriptive alt text
• Decorative images have alt=""
• Videos have captions and transcripts
• Audio content has transcripts

Step 7: Motion and animation

• Respect prefers-reduced-motion
• No flashing content above 3Hz (seizure risk)
• Animation should not distract or interfere with content

Step 8: Automated testing

Run axe-core, Lighthouse, or WAVE on every page. Automate in CI. These catch ~30–40% of accessibility issues.

Verification Requirements

• Semantic HTML used (not <div> for everything)
• All user journeys completable by keyboard only
• Tested with a screen reader
• Color contrast ratios meet WCAG AA
• Dynamic updates announced
• All images have appropriate alt text
• Reduced motion respected
• Automated accessibility tests pass in CI