รบกวนดู script ให้หน่อยค่ะ เปิดกับ Firefox ไม่ได้ค่ะ

<script>
var xmlHttp;
function createXMLHttpRequest() {
if (window.ActiveXObject) {
xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
} 
else if (window.XMLHttpRequest) {
xmlHttp = new XMLHttpRequest();
}
}
function list_namesub(id) {
var obj = document.getElementById("album");
var obj_default = '- Choose -';
if(id ==""){
while(obj.childNodes.length>0){obj.removeChild(obj.childNodes[0]);}
obj[0] = new Option(obj_default,'');}else{
var url = "get_subarist.php?id=" + id;
createXMLHttpRequest();
xmlHttp.onreadystatechange = handleStateChange;
xmlHttp.open("GET", url, true);
xmlHttp.send(null);
function handleStateChange() {
if(xmlHttp.readyState == 4) {
if(xmlHttp.status == 200) {
var results = xmlHttp.responseText;
while(obj.childNodes.length>0){obj.removeChild(obj.childNodes[0]);}
arr_list=results.split("/");
if(arr_list.length-1!=0){
for (var i=0; i < eval(arr_list.length-1); i++) {
shop_arr=arr_list[i].split(",");
obj.options[i] = new Option(shop_arr[0],shop_arr[1]); 
}}else{
while(obj.childNodes.length>0){obj.removeChild(obj.childNodes[0]);}
obj[0] = new Option(obj_default,'');
}
}
}}
}}
</script>