NodeJS Sctring decryption

I've got a short script who encrypts some strings and build final encrypted string out of it

My goal is to make a decrypted for it.

I'll provide you the encoding script and I except from you to beeing able to make a script who will decode them.

I'll pay only someone who will be able to show me that is actually able to decrypt the string, I'll not pay you to start studying it.

I'll test your decryption method, with several different encoded payloads and if everything is good I'll pay you.

Please do not come to me if you are not skilled enough for this project. I do not pay upfront.