Code:
<html>
<script type="text/javascript">
function check(ref){
bool = false;
for (i=0; i < ref.elements.length; i++) {
if (ref.elements[i].type == 'checkbox')
if (ref.elements[i].checked)
bool = true;
}
return bool;
}
</script>
<form action="" onSubmit="return(check(this));">
<input type="checkbox" name="checkbox1" />
<input type="checkbox" name="checkbox2" />
<input type="checkbox" name="checkbox3" />
<input type="checkbox" name="checkbox4" />
<input type="submit" value="try" />
</form>
</html>
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