Stream-selector NPM

stream-selector

A stream which lets you choose where to send the data based on the first chunk received

Installation

npm i --save stream-selector
or
yarn add stream-selector

Usage

var StreamSelector = require('stream-selector');

// create / get destination streams
someStream = createSomeStream();
someOtherStream = createSomeOtherStream();
someDefaultStream = createSomeDefaultStream();

function selectStream (firstChunk) {
  switch (firstChunk[0]) {
    case 0x00:
      return someStream;
    case 0x42:
      return someOtherStream;
    default:
      return someDefaultStream;
  }
}

// create selector stream
var selector = new StreamSelector(selectStream);

// when data is written tyo selector, it will use selectStream() to decide where the data should go
process.stdin.pipe(selector);

API

`new StreamSelector([options])` => `StreamSelector`

Create a new writable stream which will select a sub-stream to pipe all of the data to. If you pass your selector method as the first parameter then options will be initialized with that value.

The result stream is a passthrough stream, however it will not write any data unless the stream selected is also readable.

options (Object):
- selector: (function (chunk, encoding, callback) The method to use to choose which stream to use. You can either return the stream directly or use the callback. Note that if you return nothing, you must use the callback else the stream will infinitely hang. The data will be buffered until the decision is made.
- minBuffer: (optional Integer) The number of bytes to read in before bothering to call the selector funciton. This is useful if you need a larger header of your data before a decision can be made. The data will be buffered until the decision is made.