Await doesn’t wait for the function to end + Node.js

I’m new to Node.js and was trying to get a lease from azure blob.

const leaseID = await acquireLease(container,blobName);
const result = await download(blob);

and acquireLease method is

const acquireLease = async function(container,blobName){

    var leaseID;

        blobService.acquireLease(container,blobName ,function(error,result,response){

            if(!error) {

                // Got lease

                 leaseID =  result.id;
              }

        })

        return(leaseID);
}

exports.acquireLease = acquireLease;

but before the acquireLease method gets completed and leaseID is got, the next main method

const result = await download(blob);

gets executed.
I tried promises but couldn’t succeed.

const acquireLease = async function(container,blobName){

    var leaseID;

    return new Promise((resolve,reject)=>{

        blobSvc.acquireLease(container,blobName ,function(error,result,response){

            if(!error) {

                // Got lease

                 leaseID =  result.id;
              }

        })

        resolve(leaseID);

    })

}

exports.acquireLease = acquireLease;

Any suggestions or help appreciated.

Answers:

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Method 1

You were really close with your Promise version! You just need to call resolve and reject at the right times.

Presumably, if error is truthy, then you should reject. Otherwise, it’s safe to assume your result is valid and you can resolve the promise with result.id. There is no need for a leaseID variable. Also, if the function just returns a Promise, there’s no need to mark it async.

const acquireLease = function (container, blobName) {
    return new Promise((resolve, reject) => {
        blobSvc.acquireLease(container, blobName, function (error, result, response) {
            if (error) {
                reject(error)
            } else {
                resolve(result.id)
            }
        })
    })
}

exports.acquireLease = acquireLease;

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0