Dialog (Modal)
A window overlaid on the primary window, rendering the content underneath inert.
🤖 AI Implementation GuideDemo
Basic Dialog
A simple modal dialog with title, description, and close functionality.
This is the main content of the dialog. You can place any content here, such as text, forms, or other components.
Press Escape or click outside to close.
Without Description
A dialog with only a title and content.
This dialog has no description, only a title and content.
Accessibility Features
WAI-ARIA Roles
| Role | Target Element | Description |
|---|---|---|
dialog | Dialog container | Indicates the element is a dialog window |
WAI-ARIA dialog role (opens in new tab)
WAI-ARIA Properties
| Attribute | Target | Values | Required | Description |
|---|---|---|---|---|
aria-modal | dialog | true | Yes | Indicates this is a modal dialog |
aria-labelledby | dialog | ID reference to title element | Yes | References the dialog title |
aria-describedby | dialog | ID reference to description | No | References optional description text |
Focus Management
| Event | Behavior |
|---|---|
| Dialog opens | Focus moves to first focusable element inside the dialog |
| Dialog closes | Focus returns to the element that triggered the dialog |
| Focus trap | Tab/Shift+Tab cycles through focusable elements within the dialog only |
| Background | Content outside dialog is made inert (not focusable or interactive) |
Keyboard Support
| Key | Action |
|---|---|
| Tab | Move focus to next focusable element within dialog. When focus is on the last element, moves to first. |
| Shift + Tab | Move focus to previous focusable element within dialog. When focus is on the first element, moves to last. |
| Escape | Close the dialog and return focus to trigger element |
Additional Notes
- The dialog title is required for accessibility and should clearly describe the purpose of the dialog
- Page scrolling is disabled while the dialog is open
- Clicking the overlay (background) closes the dialog by default
- The close button has an accessible label for screen readers
Source Code
Dialog.tsx
import React, {
createContext,
useCallback,
useContext,
useEffect,
useId,
useRef,
useState,
} from 'react';
import { createPortal } from 'react-dom';
// ============================================================================
// Context
// ============================================================================
interface DialogContextValue {
dialogRef: React.RefObject<HTMLDialogElement | null>;
open: () => void;
close: () => void;
titleId: string;
descriptionId: string;
}
const DialogContext = createContext<DialogContextValue | null>(null);
function useDialogContext() {
const context = useContext(DialogContext);
if (!context) {
throw new Error('Dialog components must be used within a DialogRoot');
}
return context;
}
// ============================================================================
// DialogRoot
// ============================================================================
export interface DialogRootProps {
children: React.ReactNode;
defaultOpen?: boolean;
onOpenChange?: (open: boolean) => void;
}
export function DialogRoot({
children,
defaultOpen = false,
onOpenChange,
}: DialogRootProps): React.ReactElement {
const dialogRef = useRef<HTMLDialogElement | null>(null);
const triggerRef = useRef<HTMLElement | null>(null);
const instanceId = useId();
const [mounted, setMounted] = useState(false);
useEffect(() => {
setMounted(true);
}, []);
// Open on mount if defaultOpen
useEffect(() => {
if (mounted && defaultOpen && dialogRef.current) {
dialogRef.current.showModal();
onOpenChange?.(true);
}
}, [mounted, defaultOpen, onOpenChange]);
const open = useCallback(() => {
if (dialogRef.current) {
const { activeElement } = document;
triggerRef.current = activeElement instanceof HTMLElement ? activeElement : null;
dialogRef.current.showModal();
onOpenChange?.(true);
}
}, [onOpenChange]);
const close = useCallback(() => {
dialogRef.current?.close();
}, []);
// Handle dialog close event (from Escape key or close() call)
// Note: mounted must be in dependencies to re-run after Dialog component mounts
useEffect(() => {
const dialog = dialogRef.current;
if (!dialog) return;
const handleClose = () => {
onOpenChange?.(false);
triggerRef.current?.focus();
};
dialog.addEventListener('close', handleClose);
return () => dialog.removeEventListener('close', handleClose);
}, [onOpenChange, mounted]);
const contextValue: DialogContextValue = {
dialogRef,
open,
close,
titleId: `${instanceId}-title`,
descriptionId: `${instanceId}-description`,
};
return <DialogContext.Provider value={contextValue}>{children}</DialogContext.Provider>;
}
// ============================================================================
// DialogTrigger
// ============================================================================
export interface DialogTriggerProps extends Omit<
React.ButtonHTMLAttributes<HTMLButtonElement>,
'onClick'
> {
children: React.ReactNode;
}
export function DialogTrigger({
children,
className = '',
...buttonProps
}: DialogTriggerProps): React.ReactElement {
const { open } = useDialogContext();
return (
<button
type="button"
className={`apg-dialog-trigger ${className}`.trim()}
onClick={open}
{...buttonProps}
>
{children}
</button>
);
}
// ============================================================================
// Dialog
// ============================================================================
export interface DialogProps {
/** Dialog title (required for accessibility) */
title: string;
/** Optional description text */
description?: string;
/** Dialog content */
children: React.ReactNode;
/** Close on overlay click */
closeOnOverlayClick?: boolean;
/** Additional CSS class */
className?: string;
}
export function Dialog({
title,
description,
children,
closeOnOverlayClick = true,
className = '',
}: DialogProps): React.ReactElement | null {
const { dialogRef, close, titleId, descriptionId } = useDialogContext();
const [mounted, setMounted] = useState(false);
useEffect(() => {
setMounted(true);
}, []);
const handleDialogClick = useCallback(
(event: React.MouseEvent<HTMLDialogElement>) => {
// Close on backdrop click
if (closeOnOverlayClick && event.target === event.currentTarget) {
close();
}
},
[closeOnOverlayClick, close]
);
// SSR safety
if (typeof document === 'undefined') return null;
if (!mounted) return null;
return createPortal(
<dialog
ref={dialogRef}
className={`apg-dialog ${className}`.trim()}
aria-labelledby={titleId}
aria-describedby={description ? descriptionId : undefined}
onClick={handleDialogClick}
>
<div className="apg-dialog-header">
<h2 id={titleId} className="apg-dialog-title">
{title}
</h2>
<button
type="button"
className="apg-dialog-close"
onClick={close}
aria-label="Close dialog"
>
<svg
xmlns="http://www.w3.org/2000/svg"
width="24"
height="24"
viewBox="0 0 24 24"
fill="none"
stroke="currentColor"
strokeWidth="2"
strokeLinecap="round"
strokeLinejoin="round"
aria-hidden="true"
>
<line x1="18" y1="6" x2="6" y2="18" />
<line x1="6" y1="6" x2="18" y2="18" />
</svg>
</button>
</div>
{description && (
<p id={descriptionId} className="apg-dialog-description">
{description}
</p>
)}
<div className="apg-dialog-body">{children}</div>
</dialog>,
document.body
);
}
// ============================================================================
// Exports
// ============================================================================
export default {
Root: DialogRoot,
Trigger: DialogTrigger,
Content: Dialog,
}; Usage
Example
import { DialogRoot, DialogTrigger, Dialog } from './Dialog';
function App() {
return (
<DialogRoot onOpenChange={(open) => console.log('Dialog:', open)}>
<DialogTrigger>Open Dialog</DialogTrigger>
<Dialog
title="Dialog Title"
description="Optional description text"
>
<p>Dialog content goes here.</p>
</Dialog>
</DialogRoot>
);
} API
DialogRoot Props
| Prop | Type | Default | Description |
|---|---|---|---|
children | ReactNode | required | DialogTrigger and Dialog components |
defaultOpen | boolean | false | Initial open state |
onOpenChange | (open: boolean) => void | - | Callback when open state changes |
Dialog Props
| Prop | Type | Default | Description |
|---|---|---|---|
title | string | required | Dialog title (for accessibility) |
description | string | - | Optional description text |
children | ReactNode | required | Dialog content |
closeOnOverlayClick | boolean | true | Close when clicking overlay |
Testing
Tests verify APG compliance across keyboard interaction, ARIA attributes, and accessibility requirements.
Test Categories
High Priority: APG Keyboard Interaction
| Test | Description |
|---|---|
Escape key | Closes the dialog |
High Priority: APG ARIA Attributes
| Test | Description |
|---|---|
role="dialog" | Dialog element has dialog role |
aria-modal="true" | Indicates modal behavior |
aria-labelledby | References the dialog title |
aria-describedby | References description (when provided) |
High Priority: Focus Management
| Test | Description |
|---|---|
Initial focus | Focus moves to first focusable element on open |
Focus restore | Focus returns to trigger on close |
Focus trap | Tab cycling stays within dialog (via native dialog) |
Medium Priority: Accessibility
| Test | Description |
|---|---|
axe violations | No WCAG 2.1 AA violations (via jest-axe) |
Low Priority: Props & Behavior
| Test | Description |
|---|---|
closeOnOverlayClick | Controls overlay click behavior |
defaultOpen | Initial open state |
onOpenChange | Callback fires on open/close |
className | Custom classes are applied |
Testing Tools
- Vitest (opens in new tab) - Test runner
- Testing Library (opens in new tab) - Framework-specific testing utilities
- jest-axe (opens in new tab) - Automated accessibility testing
See testing-strategy.md (opens in new tab) for full documentation.
Dialog.test.tsx
import { render, screen, within } from '@testing-library/react';
import userEvent from '@testing-library/user-event';
import { axe } from 'jest-axe';
import { describe, expect, it, vi } from 'vitest';
import { DialogRoot, DialogTrigger, Dialog } from './Dialog';
// Test wrapper component
function TestDialog({
title = 'Test Dialog',
description,
closeOnOverlayClick = true,
defaultOpen = false,
onOpenChange,
children = <p>Dialog content</p>,
}: {
title?: string;
description?: string;
closeOnOverlayClick?: boolean;
defaultOpen?: boolean;
onOpenChange?: (open: boolean) => void;
children?: React.ReactNode;
}) {
return (
<DialogRoot defaultOpen={defaultOpen} onOpenChange={onOpenChange}>
<DialogTrigger>Open Dialog</DialogTrigger>
<Dialog title={title} description={description} closeOnOverlayClick={closeOnOverlayClick}>
{children}
</Dialog>
</DialogRoot>
);
}
describe('Dialog', () => {
// 🔴 High Priority: APG Core Compliance
describe('APG: Keyboard Interaction', () => {
it('closes dialog with Escape key', async () => {
const user = userEvent.setup();
render(<TestDialog />);
// Open dialog
await user.click(screen.getByRole('button', { name: 'Open Dialog' }));
expect(screen.getByRole('dialog')).toBeInTheDocument();
// Close with Escape
await user.keyboard('{Escape}');
expect(screen.queryByRole('dialog')).not.toBeInTheDocument();
});
});
describe('APG: ARIA Attributes', () => {
it('has role="dialog"', async () => {
const user = userEvent.setup();
render(<TestDialog />);
await user.click(screen.getByRole('button', { name: 'Open Dialog' }));
expect(screen.getByRole('dialog')).toBeInTheDocument();
});
it('has aria-modal="true"', async () => {
const user = userEvent.setup();
render(<TestDialog />);
await user.click(screen.getByRole('button', { name: 'Open Dialog' }));
expect(screen.getByRole('dialog')).toHaveAttribute('aria-modal', 'true');
});
it('references title with aria-labelledby', async () => {
const user = userEvent.setup();
render(<TestDialog title="My Dialog Title" />);
await user.click(screen.getByRole('button', { name: 'Open Dialog' }));
const dialog = screen.getByRole('dialog');
const titleId = dialog.getAttribute('aria-labelledby');
expect(titleId).toBeTruthy();
expect(document.getElementById(titleId!)).toHaveTextContent('My Dialog Title');
});
it('references description with aria-describedby when present', async () => {
const user = userEvent.setup();
render(<TestDialog description="This is a description" />);
await user.click(screen.getByRole('button', { name: 'Open Dialog' }));
const dialog = screen.getByRole('dialog');
const descriptionId = dialog.getAttribute('aria-describedby');
expect(descriptionId).toBeTruthy();
expect(document.getElementById(descriptionId!)).toHaveTextContent('This is a description');
});
it('has no aria-describedby when description is absent', async () => {
const user = userEvent.setup();
render(<TestDialog />);
await user.click(screen.getByRole('button', { name: 'Open Dialog' }));
const dialog = screen.getByRole('dialog');
expect(dialog).not.toHaveAttribute('aria-describedby');
});
});
describe('APG: Focus Management', () => {
it('focuses first focusable element when opened', async () => {
const user = userEvent.setup();
render(<TestDialog />);
await user.click(screen.getByRole('button', { name: 'Open Dialog' }));
// Focus moves to first focusable element in dialog (Close button)
await vi.waitFor(() => {
expect(screen.getByRole('button', { name: 'Close dialog' })).toHaveFocus();
});
});
// Note: Testing autofocus attribute is difficult in jsdom environment
// because React's autoFocus uses its own focus management, not DOM attributes.
// Recommended to verify with browser E2E tests (Playwright).
it('restores focus to trigger when closed', async () => {
const user = userEvent.setup();
render(<TestDialog />);
const trigger = screen.getByRole('button', { name: 'Open Dialog' });
await user.click(trigger);
expect(screen.getByRole('dialog')).toBeInTheDocument();
await user.keyboard('{Escape}');
expect(trigger).toHaveFocus();
});
// Note: Focus trap is handled by native <dialog> element's showModal().
// jsdom does not implement showModal()'s focus trap behavior,
// so these tests should be verified with browser E2E tests (Playwright).
});
// 🟡 Medium Priority: Accessibility Validation
describe('Accessibility', () => {
it('has no axe violations', async () => {
const user = userEvent.setup();
const { container } = render(<TestDialog description="Description" />);
await user.click(screen.getByRole('button', { name: 'Open Dialog' }));
const results = await axe(container);
expect(results).toHaveNoViolations();
});
});
describe('Props', () => {
it('displays title', async () => {
const user = userEvent.setup();
render(<TestDialog title="Custom Title" />);
await user.click(screen.getByRole('button', { name: 'Open Dialog' }));
expect(screen.getByText('Custom Title')).toBeInTheDocument();
});
it('displays description', async () => {
const user = userEvent.setup();
render(<TestDialog description="Custom Description" />);
await user.click(screen.getByRole('button', { name: 'Open Dialog' }));
expect(screen.getByText('Custom Description')).toBeInTheDocument();
});
it('closes on overlay click when closeOnOverlayClick=true', async () => {
const user = userEvent.setup();
render(<TestDialog closeOnOverlayClick={true} />);
await user.click(screen.getByRole('button', { name: 'Open Dialog' }));
const dialog = screen.getByRole('dialog');
// Click dialog element itself (equivalent to overlay)
await user.click(dialog);
expect(screen.queryByRole('dialog')).not.toBeInTheDocument();
});
it('does not close on overlay click when closeOnOverlayClick=false', async () => {
const user = userEvent.setup();
render(<TestDialog closeOnOverlayClick={false} />);
await user.click(screen.getByRole('button', { name: 'Open Dialog' }));
const dialog = screen.getByRole('dialog');
// Click dialog element itself
await user.click(dialog);
expect(screen.getByRole('dialog')).toBeInTheDocument();
});
it('calls onOpenChange when opened and closed', async () => {
const user = userEvent.setup();
const onOpenChange = vi.fn();
render(<TestDialog onOpenChange={onOpenChange} />);
await user.click(screen.getByRole('button', { name: 'Open Dialog' }));
expect(onOpenChange).toHaveBeenCalledWith(true);
// Close with Close button
await user.click(screen.getByRole('button', { name: 'Close dialog' }));
expect(onOpenChange).toHaveBeenCalledWith(false);
});
it('initially displayed when defaultOpen=true', async () => {
render(<TestDialog defaultOpen={true} />);
expect(screen.getByRole('dialog')).toBeInTheDocument();
});
});
// 🟢 Low Priority: Extensibility
describe('HTML Attribute Inheritance', () => {
it('applies className to dialog', async () => {
const user = userEvent.setup();
render(
<DialogRoot>
<DialogTrigger>Open</DialogTrigger>
<Dialog title="Test" className="custom-class">
Content
</Dialog>
</DialogRoot>
);
await user.click(screen.getByRole('button', { name: 'Open' }));
expect(screen.getByRole('dialog')).toHaveClass('custom-class');
});
it('applies className to trigger', async () => {
render(
<DialogRoot>
<DialogTrigger className="trigger-class">Open</DialogTrigger>
<Dialog title="Test">Content</Dialog>
</DialogRoot>
);
expect(screen.getByRole('button', { name: 'Open' })).toHaveClass('trigger-class');
});
});
}); Resources
- WAI-ARIA APG: Dialog (Modal) Pattern (opens in new tab)
- AI Implementation Guide (llm.md) (opens in new tab) - ARIA specs, keyboard support, test checklist