:
<script>
function display_passengerDiv(e){
var i, passenger,
dropdown = document.getElementById('passenger_dropdown'),
numPassengers = dropdown.options.length - 1;
val = dropdown.options[e].text;
if (val.length < 1) {
passenger = 0;
} else {
passenger = parseInt(val);
}
for(i = 1; i <= numPassengers; i++) {
if (i <= passenger) {
document.getElementById('passenger' + i).style.display = "block";
} else {
document.getElementById('passenger' + i).style.display = "none";
}
}
}
</script>
<select name="#" id="passenger_dropdown"
onChange="display_passengerDiv(this.selectedIndex);">
<option selected="selected"></option>
<option >1</option>
<option >2</option>
<option >3</option>
</select>
<div id="passenger1" style="display:none;"> hey, 1 works </div>
<div id="passenger2" style="display:none;"> hey, 2 works </div>
<div id="passenger3" style="display:none;"> hey, 3 works </div>