document.formName.selectName.options[document.formName.selectName.options.length] = new Option("xx","yyyy")-----------------------------------why ???
<select id="sel"></select> <script type="text/javascript"> //<![CDATA[ var e = new Option("name", "value"); document.getElementById("sel").add(e); //]]> </script>
<script type="text/javascript">
//<![CDATA[
var e = new Option("name", "value");
document.getElementById("sel").add(e);
//]]>
</script>
<select name=seletName></select>
<input type=button value=add onclick='document.formName.selectName.options[document.formName.selectName.options.length] = new Option("xx","yyyy")'>
</form>
<select name=selectName></select>
<input type=button value=add onclick='document.formName.selectName.options[document.formName.selectName.options.length] = new Option((new Date()).toLocaleTimeString(),"yyyy",true,true)'>
</form>出现权限问题,估计你不是在同一个窗口中执行的。你 要在select所在的窗口里写这些代码