yige.org 试一个

<html>
<head>
<script type="text/javascript">
function alertDefaultSelected()
  {
  var x=document.getElementById("mySelect").selectedIndex;
  var y=document.getElementsByTagName("option");
  var txt="Is " + y[x].text + " selected by default? ";
  txt=txt + y[x].defaultSelected;
  alert(txt);
  }
</script>
</head>
<body>

<form>
Select your favorite fruit:
<select id="mySelect">
  <option>Apple</option>
  <option>Orange</option>
  <option selected="selected">Pineapple</option>
  <option>Banana</option>
</select>
<br />
<br />
<input type="button" onclick="alertDefaultSelected()"
value="Is the chosen fruit selected by default?">
</form>

</body>
</html>

结果:

编辑上面的代码，点击查看结果。

yige.org - 试一个