streaming read from a file line by line then write to another output file

stream_read_write.js

var fs = require('fs');

const INPUT = 'input.txt';
const OUTPUT = `output_${INPUT}`;

var lineReader = require('readline').createInterface({
  input: require('fs').createReadStream(INPUT)
});

var wstream = fs.createWriteStream(OUTPUT);

lineReader.on('line', function (line) {
  wstream.write(line + '\n');
});

lineReader.on('close', (input) => {
  console.log('done');
  wstream.end();
});

wstream.on('finish', function () {
  console.log('file has been written');
});