Streams continue running

streams.js

var fs = require('fs')
  , stream = require('stream');


function Through () {
  this.processed = 0;
}
Through.prototype = new stream.Transform();

function End () {}
End.prototype = new stream.Transform();


Through.prototype._transform = function (chunk, encoding, cb) {
  this.processed += chunk.length;
  console.log('Passing through', this.processed);
  this.push(chunk);
  cb();
};

End.prototype._transform = function (chunk, encoding, cb) {
  console.log('Ended');
  this.push(null);
  cb();
};



fs.createReadStream('some-large-file.txt')
  .pipe(new Through())
  .pipe(new End());

This will output 'ended' multiple times, as the readstream will read to completion