下面的例子可返回包含按钮的表单的 id - 在线编辑器

          <!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>蜜蜂教程(mifengjc.com)</title>
  <script>
    function displayResult() {
      var x = document.getElementById("button1").form.id;
      alert(x);
    }
  </script>
</head>
<body>

  <form id="form1">
    <input type="button" onclick="displayResult()" value="显示包含按钮的表单id" id="button1">
  </form>

</body>
</html>
        