Cannot return JWT token [duplicate] - node.js

Question

This question already has answers here:
How do I return the response from an asynchronous call?
(41 answers)
Closed 3 years ago.
I've built this sign in route that creates a JWT token, but outside of the function that creates it, the token is undefined, so I'm unable to use it outside of that function.
router.post('/login', (req, res) => {
const { errors, isValid } = validateLoginInput(req.body);
if (!isValid) {
return res.status(400).json(errors);
}
const email = req.body.email;
const password = req.body.password;
User.findOne({ email }).then(user => {
if (!user) {
return res.status(404).json({ emailnotfound: "Email not found"});
}
bcrypt.compare(password, user.password).then(isMatch => {
if (isMatch) {
const payload = {
id: user.id,
name: user.name
};
var token =jwt.sign(
payload,
keys.secretOrKey,
{ expiresIn: 31556926 },
(err, token) => {
res.json({
success: true,
token: "Bearer " + token
});
});
console.log(token)
} else {
return res.status(400).json({ passwordincorrect:
"Password incorrect"});
}
});
});
});
When the code hits that console.log statement, it shows that the token is undefined instead of returning the token.

Answer 1

It seems you might have a problem with the token being created. The code is not checking if the token got created successfully.
(err, token) => {
res.json({
success: true,
token: "Bearer " + token
})
}
Change this to :
(err, token) => {
if (err){
console.log("Error while creating token:"+err.message);
console.error(err);
//send an error response as well if needed.
} else {
res.json({
success: true,
token: "Bearer " + token
})
}
This will help you figure out what the problem might be.

Answer 2

The problem seems to be here:
var token =jwt.sign(
payload,
keys.secretOrKey,
{ expiresIn: 31556926 },
(err, token) => {
res.json({
success: true,
token: "Bearer " + token
});
});
Can you check the JWT library that you are using to see if it actually accepts a callback? The correct syntax on most JWT libraries for the sign function is:
var token = jwt.sign(payload, secretKey, options);
console.log("Token :" + token);
The options usually contains an expiresIn defined in seconds.