sub populate {
    my @array = (...);
    return @array;
}

##</code><code>##

# Serializes an array, a hash or a list which contains only
# strings and undefs. Everything else will be stringified.
sub serialize_string_list {
   return join('|',
      map {
         (defined($_)
            ? do { local $_=$_; s/\^/^1/g; s/\|/^2/g; $_ }
            : '^0'
         )
      } @_
   );
}

sub populate {
    my @array = (...);
    return serialize_string_list @array;
}

##</code><code>##

function do_populate_cb(s) {
    ... do something with s...
} 

##</code><code>##

// Deserializes a list serialized with serialize_string_list.
function deserialize_string_list(s) {
   var fields = s.split("|")

   var i;
   for (i=0; i<fields.length; i++) {
      if (fields[i] == "^0") {
         fields[i] = null;
      } else {
         var re;

         re = /\^2/g;
         fields[i] = fields[i].replace(re, "|");
   
         re = /\^1/g;
         fields[i] = fields[i].replace(re, "^");
      }
   }

   return fields;
}

function do_populate_cb(s) {
    var array = deserialize_string_list(s);
    var i;
    for (i=0; i<array.length; i++) {
       ... do something with array[i]...
    }
}