<select onchange="cc(this.value)">
<option>请选择
<option value=a>a
<option value=b>b
</select><br><input name=txt style="display: none">
<select name=list style="display: none"><option>新的下拉框</select><script language=javascript>
function cc(s)
{
if (s=="")return;
if (s=="a")
{
txt.style.display="";
list.style.display="none";
}
if (s=="b")
{
txt.style.display="none";
list.style.display="";
}
}
</script>
<option>请选择
<option value=a>a
<option value=b>b
</select><br><input name=txt style="display: none">
<select name=list style="display: none"><option>新的下拉框</select><script language=javascript>
function cc(s)
{
if (s=="")return;
if (s=="a")
{
txt.style.display="";
list.style.display="none";
}
if (s=="b")
{
txt.style.display="none";
list.style.display="";
}
}
</script>
function g(o){
for(i=0;i<o.options.length;i++){
if(o.options[i].value==o.value)eval(o.value).style.display=''
else
eval(o.options[i].value).style.display='none'
}
}
</script>
<select onchange=g(this)>
<option value="a">文本框</option>
<option value="b">下拉框</option>
</select><input id=a>
<select id=b style="display:none">
<option value="a">a</option>
<option value="b">b</option>
</select>
<OPTION selected></OPTION>
<OPTION value="a">a</OPTION>
<OPTION value="b">b</OPTION>
</SELECT>
<script language=javascript>
function select1_onchange() {
if (window.select1.value=="a")
window.oprate.innerHTML="<input type='text' value=a>";
else
window.oprate.innerHTML="<select style='WIDTH: 200px'><option>new_b</option></select>";
}
</script>
<OPTION selected></OPTION>
<OPTION value="a">a</OPTION>
<OPTION value="b">b</OPTION>
</SELECT>
<tr><td><div id="oprate"></div></td></tr>
<script language=javascript>
function select1_onchange() {
if (document.form.select1.value=="a")
document.all..oprate.innerHTML="<input type='text' value=a>";
else
document.all..oprate.innerHTML="<select style='WIDTH: 200px'><option>new_b</option></select>";
}
</script>