Reset meta-data on an object in S3 bucket using AWS Node SDK

gistfile1.js

            var params = {
                Bucket: 'bucketname', /* required */
                CopySource: '/bucketname/' + key, /* required */
                Key: key, /* required */
                ACL: 'public-read', /* optional */
                ContentType: 'audio/mpeg', /* optional */
                MetadataDirective: 'REPLACE',
            };
            s3.copyObject(params, function(err, data) {
                if (err) console.log(err, err.stack); // an error occurred
                else     console.log(data);           // successful response
            });