<!DOCTYPE html> <html> <head> <meta charset = "utf-8"> <title>demo</title> <link href="https://cdn.bootcss.com/bootstrap/4.0.0/css/bootstrap.min.css" 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> <label for = "idCard">身份证号：</label> <div> <input type = "text" id = "idCard"> </div> </div> </form> </body> </html>
但是如果我们没有给输入框设置label时，当其获得焦点时，屏幕阅读器会读出aria-label属性的值，aria-label不会在视觉上呈现效果。
<body> <form role = "form"> <div> <div> <input type = "text" id = "idCard" aria-label = "身份证号"> </div> </div> </form> </body> aria-labelledby <body> <div> <button type="button" data-toggle="dropdown"> 选择您的职位 <span></span> </button> <ul role="menu" aria-labelledby="dropdownMenu1"> <li role="presentation"> <a role="menuitem" tabindex="-1" href="#" >测试工程师</a> </li> <li role="presentation"> <a role="menuitem" tabindex="-1" href="#" >开发工程师</a> </li> <li role="presentation"> <a role="menuitem" tabindex="-1" href="#" >销售工程师</a> </li> </ul> </div> </body>
注：
如果一个元素同时有aria-labelledby和aria-label，读屏软件会优先读出aria-labelledby的内容
总结
以上所述是小编给大家介绍的Bootstrap的aria-label和aria-labelledby属性实例详解，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对脚本之家网站的支持！
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