nodejs read file line by line and get its content at the end

Question

I want to use nodejs to read a file line by line and then when it finishes get the returned result as a json string. I was trying to do like this, but at the end the console.log prints undefined and not the list. I got the list and the end of the promise but how do I return it to the calling function in main.js?

I have my main.js file:

var fct = require('./romlist-parser');

console.log(fct.myfunction());

and the romlist-parser.js has the following content:

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

exports.myfunction = function() {

    var promise = new Promise(function(resolve,reject) {
        var rd = readline.createInterface({
            input: fs.createReadStream('Atari 2600.txt'),
            console: false
        });

        var games = [];

        rd.on('line', function(line) {
            var arr = line.split(";");
            games.push({name:arr[0], title:arr[1]});
        });

        rd.on('close', function() {
            var json = JSON.stringify(games);
            resolve(games);
        });

    });

    promise.then((resolveResult) => {
        console.log(resolveResult);
        return resolveResult;
    });
};

Answer 1

Try this:

exports.myfunction = function() {

    var promise = new Promise(function(resolve,reject) {

        var games = [];
        var rl = readline('./Atari 2600.txt'); // provide correct file path

        rl.on('line', function (line, lineCount, byteCount) {
            // console.log(lineCount, line, byteCount);
            var arr = line.split(";");
            games.push({name:arr[0], title:arr[1]});
        })
        .on('close', function() {
            var json = JSON.stringify(games);
            resolve(games); // resolve(json); may be?? 
        })
        .on('error', function (e) {
            console.log("error", e);
            // something went wrong
        });
    });

    promise.then((resolveResult) => {
        console.log(resolveResult);
        return resolveResult;
    });
};

P.S. This code can be improved further but for sake of simplicity and your understanding answer is limited to the style/code posted in the post. Else it can vary style to style.