js改变下拉框的selectIndex后，页面没有改变，但实际上selectIndex已经改变了，这是为什么？？
大家在自己机器上执行看看，我哪里写错了
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>MyHtml.html</title> </head>
<body>
<select name="sele">
<option >1 </option>
<option >2 </option>
<option >3 </option>
</select>
<input type="submit" onclick="setSelect()">
</body>
</html><script type="text/javascript"> function setSelect(){
document.getElementsByName("sele").selected=2;
alert(document.getElementsByName("sele").selected);
}</script>
大家在自己机器上执行看看，我哪里写错了
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>MyHtml.html</title> </head>
<body>
<select name="sele">
<option >1 </option>
<option >2 </option>
<option >3 </option>
</select>
<input type="submit" onclick="setSelect()">
</body>
</html><script type="text/javascript"> function setSelect(){
document.getElementsByName("sele").selected=2;
alert(document.getElementsByName("sele").selected);
}</script>
{
document.getElementById("sele").selectedIndex=1;
alert(document.getElementById("sele").selectedIndex);
}
或
function setSelect()
{
document.getElementById("sele").options[1].selected=true;
alert(document.getElementById("sele").selectedIndex);
}