Split streams of binary data. Similar to split but for Buffers. Whereas split is String specific, this library never converts binary data into non-binary data.

It finds delimiters with native Buffer#indexOf and emits zero-copy slices of the input, so throughput is mostly bound by I/O and stream overhead — typically hundreds of MB/s to GB/s depending on line length.

import fs from 'node:fs'
import split from 'binary-split'

for await (const line of fs.createReadStream('log.txt').pipe(split())) {
  console.log(line.toString())
}

Returns a stream. You can .pipe other streams to it or .write them yourself (if you .write don't forget to .end).

The readable side is in object mode: each line is emitted as a separate Buffer (a slice of the input, without the delimiter), whether you consume it with 'data' events, .read() or for await. Empty lines are skipped.

Pass in the optional splitOn argument (a string or Buffer) to specify where to split the data. The default is '\n'. Throws if splitOn is empty.

binary-split is only possible due to the excellent work of the following collaborators:

• Max Ogden (@max-mapper)
• Volodymyr Agafonkin (@mourner)
• Martin Raifer (@tyrasd)
• Julian Gruber (@juliangruber)