Waiting for headObject to resolve before generating getSignedUrl

I am trying to check if an Object exists before generating a SignedUrl. However the SignedUrl returns before the headObject, generating a link that points to non-existing object.

    var params = {
        Bucket: bucket,
        Key: path,
    };

    var signedURL = "none";
    s3.headObject(params, function (err, metadata) {
        if (err && err.code === 'NotFound')
            params.Key = 'no_image.png';

        params.Expires = 900;
        s3.getSignedUrl('getObject', params, function (err, url) {
            signedURL = url;
            if (err)
                console.log("Generation of Signed url failed");
            else
                console.log("Generated Signed url");
        });
    });
    console.log("Generating PreSigned Link ... Success");
    return resolve(signedURL);

Looks like following code also does not work:

var someVar = s3.headObject(params);
someVar.then(() ...

How to use promises with AWS headObject?

via Sumit Kumar Ghosh