source---------------------------------------
<script type="text/javascript">
function add(){
var i = 0;
while(1){
if ( !document.getElementById( "num[" + i+"]")){
if (i == 0){
num = 0;
}
num = i;
break;
}
i++;
}
var html = document.getElementById('id').innerHTML;
html += ""+num+": ";
html +="<input type =\"button\" onclick=\"invisible('num[" +num+"]');\" id=\"num[" +num+"]\" value=\"削除\"><br/>";
document.getElementById('id').innerHTML = html;
return;
}
function invisible(id){
document.getElementById(id).style.display = 'none';
return;
}
</script>