Read and Write large files using NodeJS

gistfile1.js

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

var inputfile = "pathtofile.txt";
var outputfile = "pathtooutputfile.json";

var instream = fs.createReadStream(inputfile);
var outstream = fs.createWriteStream(outputfile, {'flags': 'a'});
outstream.readable = true;
outstream.writable = true;

var rl = readline.createInterface(instream, outstream);

rl.on("line", function(line){this.emit("pause", line);});

rl.on("pause", function(line) {
    
  console.log("pause");
    console.log("doing some work");
	
	// do some work here
	var data = JSON.stringify("yourdata":line);
  	console.log(data);
    outstream.write(data + '\n');
	
    this.emit("resume");
	
});

rl.on("resume", function() {
    console.log("resume");
});

rl.on("close", function() {
    console.log("close");
});