<!DOCTYPE>
<html>
<body onload="test()">
<select id="myList" size="10" multiple></select>
<script>
function populateList()
{
    var myList = document.getElementById("myList");
    var item;

    for (var ii = 0; ii < 20; ii++) {
        item = document.createElement("option");
        item.value = ii;
        item.appendChild(document.createTextNode("Item #" + ii));
        myList.appendChild(item);
    }
}

function test()
{
    populateList();
}
</script>
</body>
</html>