Limit number of selected values in listbox

[Doogie]

I'm using a ASP ListBox and I have it set to allow multiple selects.
I'd like to prevent the user from selecting more than a set number of
values in the list box at a time (i.e. 4). What would be the best way
to accomplish this?

[ATR2000]

Re: Limit number of selected values in listbox

http://www.experts-exchange.com/Programming/Languages/Scripting/JavaScript/Q_23384906.html

Change your <selectto

<select name="Category1 " id="Category1" onChange="valid ateListBox(4);"
multiple size="5">

then add the following script to head section

<script>
var origSelect = new Array();
function validateListBox (max){
var newSelect = new Array();
var oSelect=documen t.getElementByI d("Category1" );
var count=0;
for(i=0;i<oSele ct.length;i++){
if(oSelect.opti ons[i].selected){
newSelect.push( i);
++count;
}
}
for(i=0;i<newSe lect.length;i++ ){
//alert("Hallo="+ newSelect[i]);

}
if(count>max){
alert("You can only choose "+max+" or fewer categories");
var lastItem=0;
var match=false;
for(i=0;i<newSe lect.length;i++ ){
match=false;
for(j=0;j<origS elect.length;j+ +){
if(newSelect[i]==origSelect[j]){
match=true;
break;
}
}
if(!match){
oSelect.options[newSelect[i]].selected=false ;
break;
}
}
}else{
origSelect=newS elect;
}
}
</script>





"Doogie" <dnlwhite@dtgne t.comwrote in message
news:7dfd5627-23b2-4f34-9f5d-3a3326273871@2g 2000hsn.googleg roups.com...

I'm using a ASP ListBox and I have it set to allow multiple selects.
I'd like to prevent the user from selecting more than a set number of
values in the list box at a time (i.e. 4). What would be the best way
to accomplish this?