Streaming Boyer-Moore-Horspool searching for node.js

Usage no npm install needed!

<script type="module">
  import streamsearch from '';



streamsearch is a module for node.js that allows searching a stream using the Boyer-Moore-Horspool algorithm.

This module is based heavily on the Streaming Boyer-Moore-Horspool C++ implementation by Hongli Lai here.



npm install streamsearch


  const { inspect } = require('util');

  const StreamSearch = require('streamsearch');

  const needle = Buffer.from('\r\n');
  const ss = new StreamSearch(needle, (isMatch, data, start, end) => {
    if (data)
      console.log('data: ' + inspect(data.toString('latin1', start, end)));
    if (isMatch)

  const chunks = [
    ' bar',
    'baz, hello\r',
    '\n world.',
    '\r\n Node.JS rules!!\r\n\r\n',
  for (const chunk of chunks)

  // output:
  // data: 'foo'
  // data: ' bar'
  // match!
  // data: 'baz, hello'
  // match!
  // data: ' world.'
  // match!
  // data: ' Node.JS rules!!'
  // match!
  // data: ''
  // match!



  • maxMatches - < integer > - The maximum number of matches. Defaults to Infinity.

  • matches - < integer > - The current match count.


  • (constructor)(< mixed >needle, < function >callback) - Creates and returns a new instance for searching for a Buffer or string needle. callback is called any time there is non-matching data and/or there is a needle match. callback will be called with the following arguments:

    1. isMatch - boolean - Indicates whether a match has been found

    2. data - mixed - If set, this contains data that did not match the needle.

    3. start - integer - The index in data where the non-matching data begins (inclusive).

    4. end - integer - The index in data where the non-matching data ends (exclusive).

  • push(< Buffer >chunk) - integer - Processes chunk, searching for a match. The return value is the last processed index in chunk + 1.

  • reset() - (void) - Resets internal state. Useful for when you wish to start searching a new/different stream for example.