How can I save the value of foo from changing code in this function only?

gistfile1.js

if(request.args.game_id === undefined) {

      var foo = undefined;
      
      Game.transactById(request.args.game_id, function(err, game) {
        
          foo = game.participantDiscards(request.getUserId(), request.args.card_id_array);
          
      }, function(err, game) {

        if(err) {
          request.onError(err);
        } else {
          
          // HERE I WANT ACCESS TO foo BUT IT IS UNDEFINED HERE YET DEFINED INSIDEtransactById
          request.onSuccess(foo);
        }
      });
    }