How to Build Custom Components with Web Accessibility in Mind: A Practical Guide Based on WCAG

Who Is This Guide For?

This guide is especially useful for:

• Web developers and UI/UX designers interested in creating accessible components
• Front-end engineers required to implement accessibility based on WCAG (Web Content Accessibility Guidelines)
• Directors and managers in web production looking to incorporate accessibility requirements into projects
• Anyone aiming to create an inclusive web experience

Introduction: What Are Custom Components?

Custom components are UI parts designed and built using JavaScript, CSS, and other technologies, rather than standard HTML elements. Examples include custom-styled dropdown menus, modal windows, tab panels, and accordions.

While these enhance user experience, poorly designed custom components can pose significant accessibility barriers. This is where WCAG-based design becomes essential.

WCAG Principles for Custom Components

WCAG is based on four principles: Perceivable, Operable, Understandable, and Robust. When creating custom components, all of these principles must be considered.

Perceivable

• Content must be perceivable through various senses such as sight and hearing.
• Example: Use ARIA labels to provide screen reader users with textual information.

Operable

• The component must be fully functional using only a keyboard.
• Example: Clear focus indicators and navigation using the Tab key.

Understandable

• Component behavior should be consistent and predictable.
• Example: A menu should always be closable after it opens.

Robust

• Code must be readable by assistive technologies.
• Example: Combine appropriate HTML structure with ARIA attributes.

Accessibility Implementation Examples for Custom Components

Here are practical points to consider for common UI components:

1. Dropdown Menu

• Use role="listbox" and aria-expanded
• Enable keyboard navigation (move items with arrow keys)
• Add aria-selected="true" to selected items

2. Modal Window

• Move focus to the modal when it opens
• Hide background elements using aria-hidden="true"
• Implement close functionality with the ESC key

3. Tab Panel

• Use role="tablist", role="tab", and role="tabpanel" appropriately
• Set aria-selected="true" on the active tab
• Support arrow key navigation

4. Accordion

• Manage state using aria-controls and aria-expanded
• Design with clear visual indicators for open/close states
• Support keyboard interaction (Enter/Space key)

Testing and Verification Points for Custom Components

To ensure your components comply with WCAG, check the following:

• Can everything be operated with just a keyboard?
• Does the screen reader read content correctly?
• Are contrast ratios and visual cues sufficient?
• Is the tab order and focus movement intuitive?
• Are ARIA attributes used appropriately and sufficiently?

It’s also recommended to refer to best practices such as the WAI-ARIA Authoring Practices.

Common Issues and How to Avoid Them

Misuse of ARIA Attributes

ARIA is useful, but native HTML elements should be prioritized where possible. Adding unnecessary role attributes can cause confusion.

Over-reliance on JavaScript

Dynamically updated content may not be picked up by screen readers. Use aria-live to notify users of changes.

Accessibility Considered Too Late in Design

Adopt a “shift-left” approach and include accessibility from the design phase. Addressing it later is often too late.

Accessibility Evaluation Level and Readability

This article is structured to comply with WCAG 2.1 AA Level and aims for high readability for everyone. We’ve considered the following:

• Definitions are provided for all technical terms
• Balanced use of kanji, hiragana, and katakana
• Average sentence length is under 40 characters
• Each paragraph is clearly separated by topic

Conclusion: Who Benefits from an Accessible Web?

An accessible web benefits not only people with visual or hearing impairments, but everyone. Busy users who can only glance at content briefly, those with eye strain, older adults—many people gain from accessible design.

Properly designed custom components significantly improve the overall user experience. Let’s each commit to building a web that’s welcoming to all by keeping accessibility top of mind.

Feel free to apply the insights from this guide to your own projects.