Accessing Array From Function

<script type="text/javascript">

function popsizes(colorcode) {
var BLK=new Array();
BLK = ["2XL","3XL","4XL","5XL","LG","MD","SM","XL","XS"];

elem = document.getElementById("selcolor");
for (i=0; i<elem.options.length; i++){
sizelist = colorcode[i];
document.getElementById("selsize").options[i] = new Option(sizelist);
}}

</script>

In an event, i'm passing in "BLK" as the colorcode param. This is creating my selsize select box with B, L, K, and undefined options until the for loop finishes. ie, its taking the passed in colorcode as a literal string, instead of referencing the array. Anyone have a pointer as to how i can access the arry, instead of the literal string?