源代码:
<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>Fmpq教程(fmpq.com)</title> </head> <body> <form action="demo-form.php"> <select required> <option value="volvo">Volvo</option> <option value="saab">Saab</option> <option value="mercedes">Mercedes</option> <option value="audi">Audi</option> </select> <input type="submit"> </form> <p><b>注意：</b>几乎所有的主流浏览器都不支持 required 属性。</p><hr> <select size="3"> <option value="volvo">Volvo</option> <option value="saab">Saab</option> <option value="opel">Opel</option> <option value="audi">Audi</option> </select> </body> </html>
运行结果：
Fmpq工具