JavaScript Tutorial: Transfer/Move items from one list box to another using Javascript

<script language="javascript" type="text/javascript">
function move(fbox, tbox) {
var arrFbox = new Array();
var arrTbox = new Array();
var arrLookup = new Array();
var i;
for (i = 0; i < tbox.options.length; i++) {
arrLookup[tbox.options[i].text] = tbox.options[i].value;
arrTbox[i] = tbox.options[i].text;
}
var fLength = 0;
var tLength = arrTbox.length;
for(i = 0; i < fbox.options.length; i++) {
arrLookup[fbox.options[i].text] = fbox.options[i].value;
if (fbox.options[i].selected && fbox.options[i].value != "") {
arrTbox[tLength] = fbox.options[i].text;
tLength++;
}
else {
arrFbox[fLength] = fbox.options[i].text;
fLength++;
    }
}
arrFbox.sort();
arrTbox.sort();
fbox.length = 0;
tbox.length = 0;
var c;
for(c = 0; c < arrFbox.length; c++) {
var no = new Option();
no.value = arrLookup[arrFbox[c]];
no.text = arrFbox[c];
fbox[c] = no;
}
for(c = 0; c < arrTbox.length; c++) {
var no = new Option();
no.value = arrLookup[arrTbox[c]];
no.text = arrTbox[c];
tbox[c] = no;
    }
}
</script>
<form name="fm_transferitemsfromlistbox">
<table><tr><td>
<select multiple size="10" name="fromlist" style="width:100">
<option value="1">A</option>
<option value="2">B</option>
<option value="3">C</option>
<option value="4">D</option>
<option value="5">E</option>
<option value="6">F</option>
<option value="7">G</option>
<option value="8">H</option>
<option value="9">I</option>
<option value="10">J</option>
</select>
</td>
<td align="center" valign="middle">
<input type="button" onClick="move(this.form.tolist,this.form.fromlist)" value="<<">
<input type="button" onClick="move(this.form.fromlist,this.form.tolist)" value=">>">
</td>
<td>
<select multiple size="10" name="tolist" style="width:150">
</select>
</td></tr></table>
</form>