a.options[a.selectedIndex].disabled = true ;

[muazzez]

The following code is not working on Internet Explorer 6.0. What can I do? Thanks...
Aşağıdaki kod, İnternet Explorer 6.0'da çalışmıyor. Ne yapabilirim? Teşekkürler...

 
<script type="text/javascript">

var i = 0 ;

function addOption (a) {

var s = document.getElementById('select4');

if(a.selectedIndex >0) {
s.options[i]= new Option(a.options[a.selectedIndex].value,a.options[a.selectedIndex].text) 

a.options[a.selectedIndex].disabled = true ; 
i++ ;
}
}

</script>

<select onchange="addOption(this)">
<option value="">choose</option>
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
<option value="4">4</option>
</select>

<select onchange="addOption(this)" >
<option value="">choose</option>
<option value="10">10</option>
<option value="20">20</option>
<option value="30">30</option>
<option value="40">40</option>
</select>

<select onchange="addOption(this)" >
<option value="">choose</option>
<option value="100">100</option>
<option value="200">200</option>
<option value="300">300</option>
<option value="400">400</option>
</select>

<select id="select4">

</select>