stupid nodejs stream example

hashstream.js

var crypto = require('crypto');
var through = require('through');

exports.createHashStream = function(algorithm, input_encoding, output_encoding) {
  input_encoding = input_encoding || 'utf8';
  output_encoding = output_encoding || 'hex';
  var hashsum = crypto.createHash(algorithm || 'sha1');

  return through(function write(data) {
    hashsum.update(data, input_encoding);
  }, function end() {
    this.emit('data', hashsum.digest(output_encoding));
    this.emit('end');
  });
}

// require('fs').ReadStream(require('path').resolve(process.argv[2])).pipe(exports.createHashStream()).pipe(process.stdout);