Unable to assign value to variable using async function on node js

Question

I was trying to get jwtauthtoken from user and passing it to a getuserId() which was imported in that js file. But i was getting undefined value instead of decoded id that was returned by the function.

In the getUserId() it displays the decoded token

My console output:

user id 5f68efb234a7656

On get request : undefined

Anyone can help to me resolve the problem.

personalDetailsController.js

module.exports.personaldetail_get = async (req,res) => {

    const token = req.cookies.jwtauthtoken;

        let userId = await getUserId(token);
        console.log("On get request : "+ userId); // output On get request : undefined

    res.render('Candidate/personal', { csrfToken: req.csrfToken() });

}

getUserId.js

module.exports.getUserId =  (tokenid) => {

    const token = tokenid;

    try{

        if (token) {

            jwt.verify(token,'2308199919990823', async (err, decodedToken) => {
                if(err){
                    console.log(err);
                    return null;
                } else {
                    console.log("user id " + decodedToken.id); // Output user id 5f68efb234a7656
                    return decodedToken.id;
                }

            });
        } else {
            return null;
        }

    }
    catch(err)
    {
        console.log(err)
        return null;
    }

}

Hi, you forgot to add return at the function call jwt.verify... — bloo
– bloo, Commented Sep 18, 2020 at 7:33
Does this answer your question? How do I return the response from an asynchronous call? — Jeremy Thille
– Jeremy Thille, Commented Sep 18, 2020 at 7:37

Jeremy Thille · Accepted Answer · 2020-09-18 09:08:13Z

3

const decodedToken = await getUserId(token) means two things :

getUserId must return a Promise.
decodedToken is given by the resolution of this Promise.

getUserId = tokenid => {
    return new Promise(resolve => {
        jwt.verify(tokenid, '2308199919990823', (err, decodedToken) => resolve(decodedToken))
    })
}

edited Sep 18, 2020 at 9:08

answered Sep 18, 2020 at 7:50

Jeremy Thille

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Comments

bloo · Accepted Answer · 2020-09-18 07:46:44Z

1

you forgot the add a return on your function call...

Also the try catch block you have will not work since your verify function is asynchronous...you need to wrap this in a Promise...

module.exports.getUserId =  (tokenid) => {

    const token = tokenid;

    if (token) {
        return new Promise((reject, resolve) => {
            jwt.verify(token,'2308199919990823', async (err, decodedToken) => {
                if(err){
                    console.log(err);
                    return null;
                } else {
                    console.log("user id " + decodedToken.id); // Output user id 5f68efb234a7656
                    return resolve(decodedToken.id);
                }

            });
        });
    }
}

edited Sep 18, 2020 at 7:46

answered Sep 18, 2020 at 7:41

bloo

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4 Comments

Jeremy Thille Over a year ago

This will only return jwt.verify which is an asynchronous function. It will not return the value of the token, which is the expected result. Downvoted

bloo Over a year ago

Yeah sorry, i had just realized that this needs to be wrapped in a Promise for it to work properly

bloo Over a year ago

Made the edit, please check and verify...it should return a Promise of a token...thanks

Jeremy Thille Over a year ago

Fair enough, canceled my downvote. But you should reject() instead of return null.

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