Select option dropdown and Javascript

Question

I have this script which I use to link to other sites, but I want to make another one of these, but if I copy all this, except the Javascript, the script breakes and the selects don't go to the given urls anymore.

How could I make this work, the best possible way, with multiple select forms?

<form name="event_type_selector" method="post" action="#">
<select name="url_list" class="event-type-selector-dropdown" onchange="gotosite()">
 <option value="" selected="selected" disabled="disabled">Vælg venligst...</option>
 <optgroup label="Selection 1:">
 <option value="?value-now1">Value-Now 1</option>
 </optgroup>
 <optgroup label="Selection 2:">
 <option value="?value-now2">Value-Now 2</option>
 </optgroup>
</select>

<script language="javascript">
function gotosite() {
 var URL = document.event_type_selector.url_list.options[document.event_type_selector.url_list.selectedIndex].value; 
 window.location.href = URL;
}
</script>

Answer 1

Just pass in a reference to the <select> in the onchange event. That way you don't need to reference the SELECT from the global scope:

<select ... onchange="gotosite(this)">
function gotosite(select) {
 window.location.href = select.value;
}