小弟不会js.....别拍我...下面是我写的函数 if (document.form1.SmallClassName.value=="")
{
alert("请先指定上级分类");
document.form1.threeClassName.clear() ;
return false;
}
<select name=SmallClassName size=11></select>
<select name=threeClassName size=11></select>
{
alert("请先指定上级分类");
document.form1.threeClassName.clear() ;
return false;
}
<select name=SmallClassName size=11></select>
<select name=threeClassName size=11></select>
document.getElementById('threeClassName').length = 0;//将长度设为0,就清空了.
<select name="SmallClassName" onchange="test()">
<option></option>
<option>11</option>
<option>22</option>
<option>33</option>
</select>
function test(){
alert("a")
if (document.form1.SmallClassName.value=="")
{
alert("请先指定上级分类");
//document.form1.SmallClassName.empty() ;
document.form1.SmallClassName.innerHTML = "";//清空
return false;
}
}
这样写最好
{
alert("请先指定上级分类");
document.form1.threeClassName.options.length=0 ;
return false;
}