<select name="" id='selectId'>
<option value="0">--请选择--</option>
<option value="1">a</option>
<option value="2">b</option>
<option value="3">c</option>
</select>
<script>
$(function (){
$('#selectId').on('change',function(){
var selectId = $('#selectId option:selected');
if(selectId.val()==1){
window.open('pink.html');
}else if(selectId.val()==2){
window.open('blue.html');
}else if(selectId.val()==3){
window.open("green.html");
}
});
});
</script>