在 CSS 中隱藏元素：可訪問的方式

在 UI 中隱藏元素很常見，但以可訪問的方式這樣做可以確保您不會無意中排除某些用戶。在本文中，我們將介紹三種場景：

1. 對螢幕閱讀器隱藏元素。
2. 僅向螢幕閱讀器顯示元素。
3. 對所有使用者隱藏元素，包括螢幕閱讀器。

每個部分都包含程式碼範例和實際用例

---

對螢幕閱讀器隱藏元素

如果您希望某個元素對視力正常的使用者可見，但對螢幕閱讀器隱藏，則可以使用 aria-hidden="true" 屬性或 CSS。

<div aria-hidden="true">This content is hidden from screen readers.</div>

使用案例

1. 隱藏背景圖片
2. 不傳達有意義訊息的裝飾圖示或視覺元素。

<button>
  <span aria-hidden="true">+</span>
  Add Item
</button>

僅向螢幕閱讀器顯示元素

要讓某個元素對螢幕閱讀器可見，但對視力正常的使用者不可見，您可以使用「視覺隱藏」技術。 Tailwind CSS 為此目的提供了一個預先建置的實用程式類，僅限 sr。

<div>



<p>Writing the sr-only class in CSS would look like this<br>
</p>

<pre class="brush:php;toolbar:false">.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  margin: -1px;
  padding: 0;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

使用案例

1. 用於標記互動元素（例如輸入），而不直觀地顯示文字：
   

   <label for="username" class="sr-only">Username</label>
   <input type="text">
   
   

2. Providing additional information for screen reader users using aria-describedby
   

   <div class="sr-only">
   
   
   <li><p><strong>Hiding Input Elements for Custom Radio Buttons</strong><br>
   When creating custom radio buttons (or checkboxes), you often hide the native input element and replace it with a visually styled element. To do this accessibly, the hidden input must remain visible to screen readers.</p></li>
   
   
   <h2>
     
     
     Hiding Elements from All Users
   </h2>
   
   <p>To completely hide an element from both sighted users and screen readers, you can use display: none or visibility: hidden.<br>
   </p>
   
   <pre class="brush:php;toolbar:false">.hidden {
     display: none;
     /* or visibility: hidden; */
   }
   

   申請課程：
   

   <div>
   
   
   
   <h2>
     
     
     長話短說
   </h2>
   
   <p>下表總結了各種 CSS 屬性如何影響不同類型使用者的可見性：</p>
   <div><table>
   <thead>
   <tr>
   <th><strong>CSS Attribute</strong></th>
   <th><strong>Hides for All Users</strong></th>
   <th><strong>Hides for Sighted Users</strong></th>
   <th><strong>Hides for Screen Readers</strong></th>
   <th><strong>Notes</strong></th>
   </tr>
   </thead>
   <tbody>
   <tr>
   <td>display: none</td>
   <td>✅</td>
   <td>✅</td>
   <td>✅</td>
   <td>Completely removes the element from the visual and accessibility tree.</td>
   </tr>
   <tr>
   <td>visibility: hidden</td>
   <td>✅</td>
   <td>✅</td>
   <td>✅</td>
   <td>Hides the element visually but keeps it in the layout and accessibility tree.</td>
   </tr>
   <tr>
   <td>opacity: 0</td>
   <td>❌</td>
   <td>✅</td>
   <td>❌</td>
   <td>Makes the element fully transparent but still visible to screen readers and interactive.</td>
   </tr>
   <tr>
   <td>clip: rect(0, 0, 0, 0)</td>
   <td>✅</td>
   <td>✅</td>
   <td>❌</td>
   <td>Commonly used in the "visually hidden" technique; removes visual rendering but accessible.</td>
   </tr>
   <tr>
   <td>position: absolute; width: 1px; height: 1px;</td>
   <td>✅</td>
   <td>✅</td>
   <td>❌</td>
   <td>Used with the "visually hidden" technique; keeps elements accessible to screen readers.</td>
   </tr>
   <tr>
   <td>aria-hidden="true"</td>
   <td>❌</td>
   <td>❌</td>
   <td>✅</td>
   <td>Removes the element from the accessibility tree but leaves it visually present.</td>
   </tr>
   <tr>
   <td>overflow: hidden</td>
   <td>❌</td>
   <td>✅ (if out of bounds)</td>
   <td>❌</td>
   <td>Hides content visually if it overflows the container but does not affect screen readers.</td>
   </tr>
   <tr>
   <td>height: 0; width: 0;</td>
   <td>✅</td>
   <td>✅</td>
   <td>❌</td>
   <td>Hides content visually while keeping it accessible to screen readers.</td>
   </tr>
   <tr>
   <td>z-index: -1</td>
   <td>❌</td>
   <td>✅</td>
   <td>❌</td>
   <td>Moves the element behind others, making it invisible to sighted users but screen reader-accessible.</td>
   </tr>
   <tr>
   <td>opacity: 0; pointer-events: none;</td>
   <td>✅</td>
   <td>✅</td>
   <td>❌</td>
   <td>Makes an element fully transparent and non-interactive, but accessible to screen readers.</td>
   </tr>
   </tbody>
   </table></div>
   
   
             </div>