How to sync two s3 buckets using aws-sdk in nodejs?

Using the s3 client of aws-sdk for nodejs, I upload contents from a local directory to a remote bucket like this.

 var s3_bucket = new AWS.S3({params:{Bucket: 'bucket_name'}});
 s3_bucket.upload(params,callback)

How can 'upload' method be used for syncing 2 s3 buckets? Or is there another method available to do this? I did not find the "sync" method which is otherwise available in aws cli.

via SRINI794