measure-stream

A duplex (Transform) stream for Node that measures the data passing through it and emits that info accordingly. The following properties are available:

• chunks - The number of processed chunks up until and including the one that triggered the event.
• totalLength - The sum of all chunk lengths. Will be 0 if the chunks are something other than strings or buffers.

Install

npm i measure-stream

Usage

const MeasureStream = require('measure-stream')

const stream = new MeasureStream()
stream.on('measure', function (info) {
  console.log('chunk count:', info.chunks)
  console.log('total length:', info.totalLength)
})

// You can then use 'stream' as you normally would, e.g.
// ('source' is readable and 'target' is writable):
source.pipe(stream).pipe(target)

As you can see, just one additional .pipe() call required to make it work!

Additionally, the last measurement is always available as a stream property. For example, if all you need is the total size after a stream has been processed:

stream.on('finish', function () {
  const bytes = stream.measurements.totalLength
})