バッジ
Documentation and examples for badges, our small count and labeling component.
サンプル
Badges scale to match the size of the immediate parent element by using relative font sizing and em units.
<h1>Example heading <span class="badge badge-secondary">New</span></h1>
<h2>Example heading <span class="badge badge-secondary">New</span></h2>
<h3>Example heading <span class="badge badge-secondary">New</span></h3>
<h4>Example heading <span class="badge badge-secondary">New</span></h4>
<h5>Example heading <span class="badge badge-secondary">New</span></h5>
<h6>Example heading <span class="badge badge-secondary">New</span></h6>Badges can be used as part of links or buttons to provide a counter.
<button type="button" class="btn btn-primary">
Notifications <span class="badge badge-light">4</span>
</button>Note that depending on how they are used, badges may be confusing for users of screen readers and similar assistive technologies. While the styling of badges provides a visual cue as to their purpose, these users will simply be presented with the content of the badge. Depending on the specific situation, these badges may seem like random additional words or numbers at the end of a sentence, link, or button.
Unless the context is clear (as with the “Notifications” example, where it is understood that the “4” is the number of notifications), consider including additional context with a visually hidden piece of additional text.
<button type="button" class="btn btn-primary">
Profile <span class="badge badge-light">9</span>
<span class="sr-only">unread messages</span>
</button>文脈に応じたバリエーション
Add any of the below mentioned modifier classes to change the appearance of a badge.
<span class="badge badge-primary">Primary</span>
<span class="badge badge-secondary">Secondary</span>
<span class="badge badge-success">Success</span>
<span class="badge badge-danger">Danger</span>
<span class="badge badge-warning">Warning</span>
<span class="badge badge-info">Info</span>
<span class="badge badge-light">Light</span>
<span class="badge badge-dark">Dark</span>支援技術に意図を伝える
色を用いて意図を伝えようとしても、視覚的な表示に終わるだけで、スクリーンリーダーなど支援技術のユーザには伝わりません。色で示された情報が、内容自体（可視テキストなど）から明らかであるか、.sr-only クラスの指定された隠しテキストなどの代替手段を通じて含まれていることを保証してください。
ピル（丸薬）形式のバッジ
Use the .badge-pill modifier class to make badges more rounded (with a larger border-radius and additional horizontal padding). Useful if you miss the badges from v3.
<span class="badge badge-pill badge-primary">Primary</span>
<span class="badge badge-pill badge-secondary">Secondary</span>
<span class="badge badge-pill badge-success">Success</span>
<span class="badge badge-pill badge-danger">Danger</span>
<span class="badge badge-pill badge-warning">Warning</span>
<span class="badge badge-pill badge-info">Info</span>
<span class="badge badge-pill badge-light">Light</span>
<span class="badge badge-pill badge-dark">Dark</span>リンク
Using the contextual .badge-* classes on an <a> element quickly provide actionable badges with hover and focus states.
<a href="#" class="badge badge-primary">Primary</a>
<a href="#" class="badge badge-secondary">Secondary</a>
<a href="#" class="badge badge-success">Success</a>
<a href="#" class="badge badge-danger">Danger</a>
<a href="#" class="badge badge-warning">Warning</a>
<a href="#" class="badge badge-info">Info</a>
<a href="#" class="badge badge-light">Light</a>
<a href="#" class="badge badge-dark">Dark</a>