php如何获取javascript中的数据

[loswing]

<?php
$arr = array( 1 => 'a', 2 => 'b' );
$a = array( 1 => 'a1', 2 => 'a2', 3 => 'a3' );
$b = array( 1 => 'b1', 2 => 'b2', 3 => 'b3' );

?>
<script language=javascript>
/*获取sencd1的数值对应改变sencd2*/
function check()
{
if (document.form1.first1.value=="1")
document.form1.second2.disabled=true;
else
document.form1.second2.disabled=false;
}

</script>

<form name=form1 >
<select name=first1 onChange="check()">
<?php
foreach($arr as $key =>$value)
{
echo"<option value='".$value."'>";
echo $value;
echo "</option>";
}
?>
</select>
<br>
<select name=second2 disabled>
<?php
//该怎么做才能php接到javascript中的参数
//我想让
if($arr[]=a) $show=$a;
if($arr[]=b) $show=$b;
//
foreach($show ad $key =>$value)
{
echo"<option value='".$value."'>";
echo $value;
echo "</option>";
}
?>
</select>
</form>

[yuxiaqiao]

我也想知道

[yexing]

做成url或者form传给php