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

user_8172016 0
Viewed 33334

I'm pretty new to JavaScript and node.js and so being thrown into Promises is pretty daunting when it is required for my bot to function.

var storedUserID;
ROBLOX.getIdFromUsername(accountArg).then(function(userID) {
  message.reply("your id is " + userID);
  storedUserID = userID;
});
message.reply(storedUserID);

This is essentially what I have written out, it creates a variable called 'storedUserID' which I would like to update later. I am trying to update it in the Promise but it does not seem to work.

In the code, there is message.reply("your id is " + userID); which works as expected. It will print out to a user 'your id is [NUMBER]' so I know userID is not null.

However, when I run message.reply(storedUserID); outside of the Promise, nothing is printed as the variable is not saved. I am not sure why.

Any help would be appreciated as this is going towards my work in college! Thank you!

node.js javascript
2 Answers

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);
});
user_28015590

Because the getIdFromUsername is asynchronous, the final line where you message.reply the stored ID is run before the ID is stored.

Asynchronous functions like getIdFromUsername don't stop the following lines of code from running. If you want it to happen after the ID is returned it needs to go inside the then callback.

user_88640440
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