无法选中3的列表框:
<select onclick="(this.value==3)?this.value=this.prevalue:this.prevalue=this.value" style="width:60px">
<option value=1>1</option>
<option value=2>2</option>
<option value=3>3</option>
<option value=4>4</option>
<option value=5>5</option>
</select>
<select onclick="(this.value==3)?this.value=this.prevalue:this.prevalue=this.value" style="width:60px">
<option value=1>1</option>
<option value=2>2</option>
<option value=3>3</option>
<option value=4>4</option>
<option value=5>5</option>
</select>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<meta name="GENERATOR" content="Microsoft FrontPage 4.0">
<meta name="ProgId" content="FrontPage.Editor.Document">
<title>New Page 3</title>
<script language="jScript">
var oSelected = 0;
function check()
{
if(s1.selectedIndex != 2) oSelected = s1.selectedIndex;
else s1.selectedIndex = oSelected;
}
</script>
</head><body>
<select id="s1" onchange="check()">
<option>1</option>
<option>2</option>
<option>3</option>
<option>4</option>
<option>5</option>
</select></body></html>
看看是不是要实现这个功能?
<HTML>
<HEAD>
<TITLE> New Document </TITLE>
</HEAD>
<script language="javascript">
<!--
state = "0"
function loadMe()
{
var n = document.frm.sel.length
for (i = 0 ; i < n ; ++i)
if (document.frm.sel.options[i].selected)
{
state = document.frm.sel.options[i].value
}
}
function selChange()
{
var n = document.frm.sel.length
document.frm.preState.value = state
for (i = 0 ; i < n ; ++i)
if (document.frm.sel.options[i].selected)
{
state = document.frm.sel.options[i].value
}
}
-->
</script><BODY name="me" ONLOAD="loadMe()">
<form name="frm">
<select name="sel" ONCHANGE="selChange()">
<option name="op1" value="1" >1</option>
<option name="op1" value="2" selected>2</option>
<option name="op1" value="3">3</option>
<option name="op1" value="4">4</option>
<option name="op1" value="5">5</option>
</select>
<p>
<b>Previous State</b><br>
<input type="text" name="preState"></input>
</p>
</form>
</BODY>
</HTML>