Add confirmation box in php

<a href="?action=del_order&oid='.$result['id'].'" onclick="return del_conf()">

<script 'javascript'>
function del_conf(){
var con=confirm("Are you sure you want to delete this order?");
    if(con)
     {
     return true;   
     }else{
         return false;
         }
  }
</script>