联动菜单问题

Question

我想让菜单不要显示“==请选择==”而是直接显示第一条数据，应该怎么改呢？function changeselect1(locationid)
{
    document.form1.s2.length = 0;
    document.form1.s2.options[0] = new Option('==请选择==','');
    document.form1.s3.length = 0;
    document.form1.s3.options[0] = new Option('==请选择==','');
document.form1.s4.length = 0;
    document.form1.s4.options[0] = new Option('==请选择==','');

    for (i=0; i<subval2.length; i++)
    {
        if (subval2[i][0] == locationid)
        {document.form1.s2.options[document.form1.s2.length] = new Option(subval2[i][2],subval2[i][2]);}
    }
for (i=0; i<subval2.length; i++)
    {
        if (subval2[i][0] == locationid)
{document.form1.s3.options[document.form1.s3.length] = new Option(subval2[i][3],subval2[i][3]);}
    }
for (i=0; i<subval2.length; i++)
    {
        if (subval2[i][0] == locationid)
{document.form1.s4.options[document.form1.s4.length] = new Option(subval2[i][4],subval2[i][4]);}
    }
}
//-->
</script>

Answer 1

document.form1.s2.selectedIndex = 1;// 下表从 0 开始

Answer 2

数据是随便加的<form name="form1">
<select name="s1" onchange="changeselect1(this.value)">
<option></option>
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
</select><select name="s2"></select>
<select name="s3"></select>
<select name="s4"></select>
</form>
<script>
var subval2 = 
[
["1","a2","a3","a4","a5","a6","a7","a8"],
["2","b2","b3","b4","b5","b6","b7","b8"],
["3","c2","c3","c4","c5","c6","c7","c8"]
];
function changeselect1(locationid){ 
document.form1.s2.length = 0; 
document.form1.s2.options[0] = new Option('==请选择==',''); 
document.form1.s3.length = 0; 
document.form1.s3.options[0] = new Option('==请选择==',''); 
document.form1.s4.length = 0; 
document.form1.s4.options[0] = new Option('==请选择==','');  for (i=0; i < subval2.length; i++){ 
if (subval2[i][0] == locationid){
document.form1.s2.options[document.form1.s2.length] = new Option(subval2[i][2],subval2[i][2]);
}
} for (i=0; i < subval2.length; i++){ 
if (subval2[i][0] == locationid){
document.form1.s3.options[document.form1.s3.length] = new Option(subval2[i][3],subval2[i][3]);
}
} for (i=0; i < subval2.length; i++){
if (subval2[i][0] == locationid){
document.form1.s4.options[document.form1.s4.length] = new Option(subval2[i][4],subval2[i][4]);
}
}

document.form1.s2.selectedIndex = 1;
document.form1.s3.selectedIndex = 1;
document.form1.s4.selectedIndex = 1;
}
</script>

Answer 3

    for (i=0; i <subval2.length; i++) 
    { 
        if (subval2[i][0] == locationid) 
        {document.form1.s2.options[document.form1.s2.length] = new Option(subval2[i][2],subval2[i][2]);document.form1.s2.value=subval2[i][2]} 
    }