[raycmorgan]

I would do it in Node.js like the following:

  async.eachSeries(players, askName, function (err) {});

  // this is someplace it should go
  function askName(player, callback) {
    Ask("What's your name", function (err, name) {
      if (err) { return callback(err); }
  
      if (IsValidName(name)) {
        player.name = name;
        callback(null);
      } else {
        askName(player, callback);
      }
    });
  }

This follows Node's err convention. Note I use a bit of old fashion recursion to handle the asking for a valid name. This will not stack overflow due to the fact Ask is async. You could inline askName, but then you wouldn't have a nice little unit testable function.