<script type="text/javascript"> 
function fill_userid(){
element = document.getElementById("P2_USERNAME");
element.value=document.getElementById("P2_USERLIST");
alert(element.value);
}
</script>

$x("P2_USERNAME").value=$v("P2_USERLIST");

$x("P2_USERNAME").value=$v("P2_USERLIST");

alert($v("P2_USERLIST"));

function tryme()
{
$x("P2_USERNAME").value=$v("P2_USERLIST");
alert($v("P2_USERLIST").value);
alert($x("P2_USERNAME").value);
}

function tryme()
{
$x('P2_USERNAME').value=$v('P2_USERLIST');
alert($v('P2_USERLIST').value);
alert($x('P2_USERNAME').value);
}

<script>
 function get_select_list_xml1(pThis,pSelect){ 
    var l_Return = null;
    var l_Select = html_GetElement(pSelect);
    var get = new htmldb_Get(null,html_GetElement('pFlowId').value,
              'APPLICATION_PROCESS=CASCADING_SELECT_LIST1', 0 );
    get.add('CASCADING_SELECTLIST_ITEM_1',pThis.value);
    gReturn = get.get('XML');
    if(gReturn && l_Select){
        var l_Count = gReturn.getElementsByTagName("option").length;
        l_Select.length =  0 ;
        for(var i= 0 ;i<l_Count;i++){
            var l_Opt_Xml = gReturn.getElementsByTagName("option")[i];
            appendToSelect(l_Select, l_Opt_Xml.getAttribute('value'), 
                                     l_Opt_Xml.firstChild.nodeValue)
        }
    }
    get = null;
 }

HTP.P('<u><A HREF="#" onClick="javascript:fillUID("'||USER_ARR(I)||'")"></u>'||USER_ARR(I)||'</A><BR>');