اظن مكانه اللغات القياسية ..
كود HTML:
<form name="myform" id="myform" onsubmit="return Check()">
<input type="checkbox" name="ch" value="1" />
<input type="checkbox" name="ch" value="2" />
<input type="checkbox" name="ch" value="3" />
<input type="submit" value="Submit" />
</form>
<script type="text/javascript">
function Check()
{
isThereAnyCheck = false;
boxes = document.myform.ch
for(i = 0 ; i< boxes.length ; i++){
if( boxes[i].checked )
{
isThereAnyCheck = true;
break;
}
}
if(!isThereAnyCheck)
{
alert("You must select one!") ;return false
}else return true
}