jspm-npm

node-buffer-peek-stream

A Transform stream which lets you take a peek at the first bytes before unpiping itself and unshifting the buffer back onto the upstream stream leaving the original stream ready to be piped again onto its final destination.

npm install buffer-peek-stream

Useful if you want to inspect the start of a stream before deciding what to do with it.

This works with buffers and does no string decoding. If you know you have a string and already know its encoding then checkout peek-stream.

Usage

As a function...

var peek = require('buffer-peek-stream');
var readstream = fs.createReadStream('package.json');

peek(readstream, 65536, function (err, data, outputStream) {
  if (err) throw err;

  // outputStream is ready to be piped somewhere else
  outputStream.pipe(somewhere_else);
});

As a stream...

var PeekStream = require('buffer-peek-stream').BufferPeekStream;

var peek = new PeekStream(65536);
var readstream = fs.createReadStream('package.json');

// peek will only emit the data event once
peek.once('data', function (buf) {

  // readstream is ready to be piped somewhere else
  peek.pipe(somewhere_else);
});

readstream.pipe(peek);

// alternatively pipe `peek` here instead of in `data` callback

Licence

MIT