javascript - Variables are not being set inside the .then() part of a Promise

return the value at function passed to .then()

var storedUserID = ROBLOX.getIdFromUsername(accountArg)
                   .then(function(userID) {
                     return userID;
                   });

you can then use or change the Promise value when necessary

storedUserID = storedUserID.then(id) {
  return /* change value of Promise `storedUserID` here */
});

access and pass the value to message.reply() within .then()

storedUserID.then(function(id) {

  message.reply(id);
});

or

var storedUserID = ROBLOX.getIdFromUsername(accountArg);
// later in code
storedUserID.then(function(id) {
  message.reply(id);

});