getAttribute of value from drop down list

[maminx]

I have this script...

        var td = document.createElement('td');
    var p = document.createElement('p');
    var label = document.createElement('label');
    var span = document.createElement('span');
    var theData = document.createTextNode('Chart Of Account');
    var theSelect = document.createElement('select');
    theSelect.setAttribute('name', 'items['+item_count+'][pbdccoa]');
    var opCol = document.createElement('option');
    opCol.setAttribute('value', '');
    var opColTxt = document.createTextNode('<?php echo $this->lang->line('select_coa')?>');
    opCol.appendChild(opColTxt);
    theSelect.appendChild(opCol);
    <?php foreach($coa_list->result() as $coa): ?>                            var opCol = document.createElement('option');
    opCol.setAttribute('value', '<?php echo $coa->ccbcCoa?>');
    var opColTxt = document.createTextNode('<?php echo $coa->ccbcCoa?>');
    opCol.appendChild(opColTxt);
    theSelect.appendChild(opCol);            
    <?php endforeach; ?>
    opCol.onselect = function(){
    if (this.getAttribute('value')==null || this.getAttribute('value')==""){
        alert("Require field");
        }
    }
    span.appendChild(theData);
    label.appendChild(span);
    label.appendChild(theSelect);
    p.appendChild(label);
    td.appendChild(p);
    row.appendChild(td);
 

With this command below i want to check the value of drop down list, if user select a null value of drop down list, than it will show an alert window ("Require Field").

if (this.getAttribute('value')==null || this.getAttribute('value')==""){
        alert("Require field");
        }
}
 

But it doesn;t work well, any idea??thanks for helping me..

[rnd me]

xbrowser onchange:

<select onchange"var ti=this.selectedIndex;var op=this.options; if(op[ti].value){ alert(op[ti].value); }">

[maminx]

xbrowser onchange:

<select onchange"var ti=this.selectedIndex;var op=this.options; if(op[ti].value){ alert(op[ti].value); }">

sorry i dont understand with that, where do i must put that script??
thanks

[acoder]

onselect is only for text inputs and textareas. Use onchange on the select element, e.g.

theSelect.onchange = function() {
    if (this.value == "") alert("Required Field");
}