Split2 is a Node.js module that breaks up a stream and reassembles it so that each line is a chunk, inspired by the split module and based on Node.js core Transform. It accepts a matcher (String or RegExp) and an optional mapper function to transform each line, and can be used to read every line in a file or parse newline-delimited JSON. This module is useful for developers working with streams in Node.js who need to process data line by line.