passthrough-counter

What is passthrough-counter?

The passthrough-counter npm package is a simple utility that acts as a pass-through stream while counting the number of bytes that pass through it. It is useful in scenarios where you need to monitor the amount of data being processed in a stream pipeline.

What are passthrough-counter's main functionalities?

Counting Bytes in a Stream

This feature allows you to count the number of bytes that pass through a stream. In this example, data from 'input.txt' is read, passed through the counter, and written to 'output.txt'. The total number of bytes is logged once the stream finishes.

const PassThroughCounter = require('passthrough-counter');
const fs = require('fs');

const counter = new PassThroughCounter();

fs.createReadStream('input.txt')
  .pipe(counter)
  .pipe(fs.createWriteStream('output.txt'))
  .on('finish', () => {
    console.log(`Total bytes: ${counter.length}`);
  });

Other packages similar to passthrough-counter

through2

The through2 package provides a thin wrapper around Node.js streams2 Transform to avoid explicit subclassing noise. It allows you to create a transform stream that can modify the data passing through it. Unlike passthrough-counter, through2 does not specifically count bytes but can be used to implement similar functionality with additional code.

stream-counter

The stream-counter package is designed to count the number of bytes passing through a stream. It is similar to passthrough-counter in its primary functionality but offers additional features such as counting objects in object mode.

byte-stream

The byte-stream package provides a way to work with byte streams in Node.js. It includes utilities for counting bytes, transforming data, and more. It offers more comprehensive functionality compared to passthrough-counter, which focuses solely on counting bytes.

README

Passthrough Counter

Creates a PassThrough stream that also counts the stream's buffer length.

var Counter = require('passthrough-counter')

var stream = fs.createReadStream('package.json')
var output = fs.createWriteStream('package.json.gz')

stream
.pipe(zlib.createGzip())
.pipe(Counter)
.once('finish', function () {
  console.log('final gzipped length is ' + this.length)
})
.pipe(output)

API

new Counter(options)

new is optional. options is optional and is passed into the Stream.Transform constructor.

counter.length

The total number of bytes pass through the stream. You can check this once finish is emitted.

License

The MIT License (MIT)

Copyright (c) 2013 Jonathan Ong [e-mail]

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.