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

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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!

Answer

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);
});