wtf.js

var fs = require('fs');
var through2 = require('through2');
var csv = require('fast-csv');
var util = require('util');

var writeStream = fs.createWriteStream('out.csv');

var progress = {
  total: 0,
  done: 0
};

//the following reads thing.csv (a 50k line csv), parses it, counts the lines, stringifies it, and counts the lines again
var csvStream = fs.createReadStream('thing.csv')
  .pipe(csv({headers: true, delimiter: '|'}))
  .pipe(through2.obj(function(chunk, enc, cb){
    progress.total++;
    cb(null, chunk);
  }))
  .pipe(csv.createWriteStream())
  .pipe(through2(function(chunk, enc, cb){
    progress.done++;
    console.log(progress.done, progress.total);
    cb(null, chunk);
  }));

var stockReadablePipe = require('stream').Readable.prototype.pipe;
var stockPipe = require('stream').prototype.pipe;

//This works
stockPipe.call(csvStream, writeStream);

//This doesn't work
//stockReadablePipe.call(csvStream, writeStream);

//This doesn't work (same as above)
//csvStream.pipe(writeStream);

//This works
/*csvStream.on('data', function(chunk, enc){
  if (!writeStream.write(chunk, enc)) {
    csvStream.pause();
  }
});

writeStream.on('drain', function(){
  csvStream.resume();
});

csvStream.on('end', function(){
  writeStream.end();
});*/