fmpq.com
源代码：
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<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>Fmpq教程(fmpq.com)</title> </head> <body> <form action="form_action.asp"> 名: <input type="text" id="myText" name="fname"> <input type="submit"> </form> <p>点击 "点我" 按钮为文本域设置 required 属性。</p> <p><strong>提示：</strong> 在点击“点我”按钮后点击 "Submit" 按钮查看效果。</p> <button onclick="myFunction()">点我</button> <p id="demo"></p> <script> function myFunction() { document.getElementById("myText").required = true; document.getElementById("demo").innerHTML = " required 属性已设置。文本域在表单提交时是必填字段。"; } </script> </body> </html>
运行结果