The zlib module provides compression functionality implemented using Gzip and Deflate/Inflate. It is the part of nodejs core module written in c++ . So the problem is we can't use this module outside of nodejs. so now this package help you to use all zlib functionality in real Javascript and React Native
You can use this library like jquery and other normal javascript library the file index.js file can add to your javascript and use as per this web site and you can use buffer.js file to access Buffer class in react-native and javascript this class also a native nodejs implementation you can use test.js as an example.js