Toggle Button

A two-state button that can be either "pressed" or "not pressed".

Demo

Accessibility Features

WAI-ARIA Roles

Role	Target Element	Description
`button`	Button element	Indicates a widget that triggers an action when activated

WAI-ARIA States

`aria-pressed`

Target Element: button
Values: true | false
Required: Yes
Change Trigger: Click, Enter, Space

Keyboard Support

Key	Action
`Space`	Toggle the button state
`Enter`	Toggle the button state

Toggle buttons must have an accessible name via visible label text, aria-label, or aria-labelledby.
Use type=“button” to prevent accidental form submission.
Tri-state buttons may use aria-pressed=“mixed” for partially selected state (e.g., “Select All” when some items selected).

Implementation Notes

Structure:
<button type="button" aria-pressed="false">
  Mute
</button>

State Changes:
- Initial: aria-pressed="false" (not pressed)
- After click: aria-pressed="true" (pressed)

Use type="button":
- Prevents accidental form submission
- Native <button> defaults to type="submit"

Tri-state (rare):
- aria-pressed="mixed" for partially selected state
- Example: "Select All" when some items selected

Toggle Button structure and state changes

References

Source Code

ToggleButton.vue

<template>
  <button
    type="button"
    class="apg-toggle-button"
    :aria-pressed="pressed"
    :disabled="props.disabled"
    v-bind="$attrs"
    @click="handleClick"
  >
    <span class="apg-toggle-button-content">
      <slot />
    </span>
    <span class="apg-toggle-indicator" aria-hidden="true">
      <template v-if="pressed">
        <slot name="pressed-indicator">{{ props.pressedIndicator ?? '●' }}</slot>
      </template>
      <template v-else>
        <slot name="unpressed-indicator">{{ props.unpressedIndicator ?? '○' }}</slot>
      </template>
    </span>
  </button>
</template>

<script setup lang="ts">
import { ref } from 'vue';

// Inherit all HTML button attributes
defineOptions({
  inheritAttrs: false,
});

export interface ToggleButtonProps {
  /** Initial pressed state */
  initialPressed?: boolean;
  /** Whether the button is disabled */
  disabled?: boolean;
  /** Callback fired when toggle state changes */
  onToggle?: (pressed: boolean) => void;
  /** Custom indicator for pressed state (default: "●") */
  pressedIndicator?: string;
  /** Custom indicator for unpressed state (default: "○") */
  unpressedIndicator?: string;
}

const props = withDefaults(defineProps<ToggleButtonProps>(), {
  initialPressed: false,
  disabled: false,
  onToggle: undefined,
  pressedIndicator: undefined,
  unpressedIndicator: undefined,
});

const emit = defineEmits<{
  toggle: [pressed: boolean];
}>();

defineSlots<{
  default(): unknown;
  'pressed-indicator'(): unknown;
  'unpressed-indicator'(): unknown;
}>();

const pressed = ref(props.initialPressed);

const handleClick = () => {
  const newPressed = !pressed.value;
  pressed.value = newPressed;

  // Call onToggle prop if provided (for React compatibility)
  props.onToggle?.(newPressed);
  // Emit Vue event
  emit('toggle', newPressed);
};
</script>

Usage

Example

<script setup>
import ToggleButton from './ToggleButton.vue';
import { Volume2, VolumeOff } from 'lucide-vue-next';

const handleToggle = (pressed) => {
  console.log('Muted:', pressed);
};
</script>

<template>
  <ToggleButton
    :initial-pressed="false"
    @toggle="handleToggle"
  >
    <template #pressed-indicator>
      <VolumeOff :size="20" />
    </template>
    <template #unpressed-indicator>
      <Volume2 :size="20" />
    </template>
    Mute
  </ToggleButton>
</template>

API

Prop	Type	Default	Description
`initialPressed`	boolean	false	Initial pressed state
`pressedIndicator`	string	"●"	Custom indicator for pressed state
`unpressedIndicator`	string	"○"	Custom indicator for unpressed state

Slots

Slot	Default	Description
`default`	-	Button label content
`pressed-indicator`	"●"	Custom indicator for pressed state
`unpressed-indicator`	"○"	Custom indicator for unpressed state

All other attributes are passed to the underlying <button> element via v-bind="$attrs".

Custom Events

Event	Detail	Description
`toggle`	boolean	Emitted when state changes

Testing

Tests verify APG compliance across keyboard interaction, ARIA attributes, and accessibility requirements. The Toggle Button component uses a two-layer testing strategy.

Testing Strategy

Unit Tests (Testing Library)

Verify component rendering and interactions using framework-specific Testing Library utilities. These tests ensure correct component behavior in isolation.

HTML structure and element hierarchy
Initial attribute values (aria-pressed, type)
Click event handling and state toggling
CSS class application

E2E Tests (Playwright)

Verify component behavior in a real browser environment across all four frameworks. These tests cover interactions that require full browser context.

Keyboard interactions (Space, Enter)
aria-pressed state toggling
Disabled state behavior
Focus management and Tab navigation
Cross-framework consistency

Test Categories

High Priority: APG Keyboard Interaction (E2E)

test	description
`Space key toggles`	Pressing Space toggles the button state
`Enter key toggles`	Pressing Enter toggles the button state
`Tab navigation`	Tab key moves focus between buttons
`Disabled Tab skip`	Disabled buttons are skipped in Tab order

High Priority: APG ARIA Attributes (E2E)

test	description
`role="button"`	Has implicit button role (via <code><button></code>)
`aria-pressed initial`	Initial state is aria-pressed="false"
`aria-pressed toggle`	Click changes aria-pressed to true
`type="button"`	Explicit button type prevents form submission
`disabled state`	Disabled buttons don't change state on click

Medium Priority: Accessibility (E2E)

test	description
`axe violations`	No WCAG 2.1 AA violations (via jest-axe)
`accessible name`	Button has an accessible name from content

Low Priority: HTML Attribute Inheritance (Unit)

test	description
`className merge`	Custom classes are merged with component classes
`data-* attributes`	Custom data attributes are passed through

Testing Tools

Vitest (opens in new tab) - Test runner for unit tests
Testing Library (opens in new tab) - Framework-specific testing utilities (React, Vue, Svelte)
Playwright (opens in new tab) - Browser automation for E2E tests
axe-core/playwright (opens in new tab) - Automated accessibility testing in E2E

See testing-strategy.md (opens in new tab) for full documentation.

ToggleButton.test.vue.ts

import { render, screen } from '@testing-library/vue';
import userEvent from '@testing-library/user-event';
import { axe } from 'jest-axe';
import { describe, expect, it, vi } from 'vitest';
import ToggleButton from './ToggleButton.vue';

describe('ToggleButton (Vue)', () => {
  // 🔴 High Priority: APG 準拠の核心
  describe('APG: キーボード操作', () => {
    it('Space キーでトグルする', async () => {
      const user = userEvent.setup();
      render(ToggleButton, {
        slots: { default: 'Mute' },
      });
      const button = screen.getByRole('button');

      expect(button).toHaveAttribute('aria-pressed', 'false');
      button.focus();
      await user.keyboard(' ');
      expect(button).toHaveAttribute('aria-pressed', 'true');
    });

    it('Enter キーでトグルする', async () => {
      const user = userEvent.setup();
      render(ToggleButton, {
        slots: { default: 'Mute' },
      });
      const button = screen.getByRole('button');

      expect(button).toHaveAttribute('aria-pressed', 'false');
      button.focus();
      await user.keyboard('{Enter}');
      expect(button).toHaveAttribute('aria-pressed', 'true');
    });

    it('Tab キーでフォーカス移動可能', async () => {
      const user = userEvent.setup();
      render({
        components: { ToggleButton },
        template: `
          <ToggleButton>Button 1</ToggleButton>
          <ToggleButton>Button 2</ToggleButton>
        `,
      });

      await user.tab();
      expect(screen.getByRole('button', { name: 'Button 1' })).toHaveFocus();
      await user.tab();
      expect(screen.getByRole('button', { name: 'Button 2' })).toHaveFocus();
    });

    it('disabled 時は Tab キースキップ', async () => {
      const user = userEvent.setup();
      render({
        components: { ToggleButton },
        template: `
          <ToggleButton>Button 1</ToggleButton>
          <ToggleButton disabled>Button 2</ToggleButton>
          <ToggleButton>Button 3</ToggleButton>
        `,
      });

      await user.tab();
      expect(screen.getByRole('button', { name: 'Button 1' })).toHaveFocus();
      await user.tab();
      expect(screen.getByRole('button', { name: 'Button 3' })).toHaveFocus();
    });
  });

  describe('APG: ARIA 属性', () => {
    it('role="button" を持つ（暗黙的）', () => {
      render(ToggleButton, {
        slots: { default: 'Mute' },
      });
      expect(screen.getByRole('button')).toBeInTheDocument();
    });

    it('初期状態で aria-pressed="false"', () => {
      render(ToggleButton, {
        slots: { default: 'Mute' },
      });
      const button = screen.getByRole('button');
      expect(button).toHaveAttribute('aria-pressed', 'false');
    });

    it('クリック後に aria-pressed="true" に変わる', async () => {
      const user = userEvent.setup();
      render(ToggleButton, {
        slots: { default: 'Mute' },
      });
      const button = screen.getByRole('button');

      expect(button).toHaveAttribute('aria-pressed', 'false');
      await user.click(button);
      expect(button).toHaveAttribute('aria-pressed', 'true');
    });

    it('type="button" が設定されている', () => {
      render(ToggleButton, {
        slots: { default: 'Mute' },
      });
      const button = screen.getByRole('button');
      expect(button).toHaveAttribute('type', 'button');
    });

    it('disabled 状態で aria-pressed 変更不可', async () => {
      const user = userEvent.setup();
      render(ToggleButton, {
        props: { disabled: true },
        slots: { default: 'Mute' },
      });
      const button = screen.getByRole('button');

      expect(button).toHaveAttribute('aria-pressed', 'false');
      await user.click(button);
      expect(button).toHaveAttribute('aria-pressed', 'false');
    });
  });

  // 🟡 Medium Priority: アクセシビリティ検証
  describe('アクセシビリティ', () => {
    it('axe による WCAG 2.1 AA 違反がない', async () => {
      const { container } = render(ToggleButton, {
        slots: { default: 'Mute' },
      });
      const results = await axe(container);
      expect(results).toHaveNoViolations();
    });

    it('アクセシブルネームが設定されている', () => {
      render(ToggleButton, {
        slots: { default: 'Mute Audio' },
      });
      expect(screen.getByRole('button', { name: /Mute Audio/i })).toBeInTheDocument();
    });
  });

  describe('Props', () => {
    it('initialPressed=true で押下状態でレンダリングされる', () => {
      render(ToggleButton, {
        props: { initialPressed: true },
        slots: { default: 'Mute' },
      });
      const button = screen.getByRole('button');
      expect(button).toHaveAttribute('aria-pressed', 'true');
    });

    it('onToggle が状態変化時に呼び出される', async () => {
      const handleToggle = vi.fn();
      const user = userEvent.setup();
      render(ToggleButton, {
        props: { onToggle: handleToggle },
        slots: { default: 'Mute' },
      });

      await user.click(screen.getByRole('button'));
      expect(handleToggle).toHaveBeenCalledWith(true);

      await user.click(screen.getByRole('button'));
      expect(handleToggle).toHaveBeenCalledWith(false);
    });

    it('@toggle イベントが状態変化時に発火する', async () => {
      const handleToggle = vi.fn();
      const user = userEvent.setup();
      render(ToggleButton, {
        props: { onToggle: handleToggle },
        slots: { default: 'Mute' },
      });

      await user.click(screen.getByRole('button'));
      expect(handleToggle).toHaveBeenCalledWith(true);
    });
  });

  // 🟢 Low Priority: 拡張性
  describe('HTML 属性継承', () => {
    it('class が正しくマージされる', () => {
      render(ToggleButton, {
        attrs: { class: 'custom-class' },
        slots: { default: 'Mute' },
      });
      const button = screen.getByRole('button');
      expect(button).toHaveClass('custom-class');
      expect(button).toHaveClass('apg-toggle-button');
    });

    it('data-* 属性が継承される', () => {
      render(ToggleButton, {
        attrs: { 'data-testid': 'custom-toggle' },
        slots: { default: 'Mute' },
      });
      expect(screen.getByTestId('custom-toggle')).toBeInTheDocument();
    });
  });
});

Resources

WAI-ARIA APG: Button Pattern (opens in new tab)
AI Implementation Guide (llm.md) (opens in new tab) - ARIA specs, keyboard support, test checklist