下面是连同 HTML 表单的完整代码 - 在线编辑器

          <!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
</head>
<head>
  <script>
    function validateForm() {
      var x = document.forms["myForm"]["email"].value;
      var atpos = x.indexOf("@");
      var dotpos = x.lastIndexOf(".");
      if (atpos < 1 || dotpos < atpos + 2 || dotpos + 2 >= x.length) {
        alert("不是一个有效的 e-mail 地址");
        return false;
      }
    }
  </script>
</head>
<body>

  <form name="myForm" action="/plays/html-form-submit" onsubmit="return validateForm();" method="post">
    Email: <input type="text" name="email">
    <input type="submit" value="提交">
  </form>

</body>
</html>
        