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Bootstrap的aria-label和aria-labelledby屬性實(shí)例詳解

更新時(shí)間：2018年11月02日 10:21:35 作者：Mr.zengcx

這篇文章主要介紹了Bootstrap的aria-label和aria-labelledby屬性實(shí)例詳解,需要的朋友可以參考下

aria-label

正常情況下，form表單的input組件都有對(duì)應(yīng)的label.當(dāng)input組件獲取到焦點(diǎn)時(shí)，屏幕閱讀器會(huì)讀出相應(yīng)的label里的文本。

<!DOCTYPE html>
<html>
<head>
  <meta charset = "utf-8">
  <title>demo</title>
  <link rel="stylesheet"  rel="external nofollow" integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" crossorigin="anonymous">
  <script src="https://cdn.bootcss.com/jquery/3.2.1/jquery.slim.min.js" integrity="sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN" crossorigin="anonymous"></script>
 <script src="https://cdn.bootcss.com/popper.js/1.12.9/umd/popper.min.js" integrity="sha384-ApNbgh9B+Y1QKtv3Rn7W3mgPxhU9K/ScQsAP7hUibX39j7fakFPskvXusvfa0b4Q" crossorigin="anonymous"></script>
 <script src="https://cdn.bootcss.com/bootstrap/4.0.0/js/bootstrap.min.js" integrity="sha384-JZR6Spejh4U02d8jOt6vLEHfe/JQGiRRSQQxSfFWpi1MquVdAyjUar5+76PVCmYl" crossorigin="anonymous"></script>
  <style type="text/css">
    body{padding: 20px;}
  </style>
</head>
<body>
  <form role = "form">
    <div class="form-group col-lg-3 form-horizontal">
      <label for = "idCard" class="control-label col-lg-5">身份證號(hào)：</label>
      <div class="col-lg-7">
        <input type = "text" id = "idCard" class="form-control">
      </div>    
    </div>  
  </form>
</body>
</html>

但是如果我們沒有給輸入框設(shè)置label時(shí)，當(dāng)其獲得焦點(diǎn)時(shí)，屏幕閱讀器會(huì)讀出aria-label屬性的值，aria-label不會(huì)在視覺上呈現(xiàn)效果。

<body>
  <form role = "form">
    <div class="form-group col-lg-3 form-horizontal">
      <div class="col-lg-7">
        <input type = "text" id = "idCard" class="form-control" aria-label = "身份證號(hào)">
      </div>    
    </div>  
  </form>
</body>

aria-labelledby
<body>
  <div class="dropdown">
    <button type="button" class="btn dropdown-toggle" id="dropdownMenu1" 
     data-toggle="dropdown">
     選擇您的職位
     <span class="caret"></span>
    </button>
    <ul class="dropdown-menu" role="menu" aria-labelledby="dropdownMenu1">
     <li role="presentation">
       <a role="menuitem" tabindex="-1" href="#" rel="external nofollow" rel="external nofollow" rel="external nofollow" >測(cè)試工程師</a>
     </li>
     <li role="presentation">
       <a role="menuitem" tabindex="-1" href="#" rel="external nofollow" rel="external nofollow" rel="external nofollow" >開發(fā)工程師</a>
     </li>
     <li role="presentation">
       <a role="menuitem" tabindex="-1" href="#" rel="external nofollow" rel="external nofollow" rel="external nofollow" >銷售工程師</a>
     </li>     
    </ul>
  </div>
</body>

注：

如果一個(gè)元素同時(shí)有aria-labelledby和aria-label，讀屏軟件會(huì)優(yōu)先讀出aria-labelledby的內(nèi)容

總結(jié)

以上所述是小編給大家介紹的Bootstrap的aria-label和aria-labelledby屬性實(shí)例詳解，希望對(duì)大家有所幫助，如果大家有任何疑問(wèn)請(qǐng)給我留言，小編會(huì)及時(shí)回復(fù)大家的。在此也非常感謝大家對(duì)腳本之家網(wǎng)站的支持！

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