I have created an express app which successfully displays JSON on Windows - I have had no problem on Firefox or Chrome. However, when I try to run the same code on my linux setup (Debian) or deploy it on Heroku, receives an empty array: []. How can I get it to display on more than just windows? Here is the js file:

var express = require('express');
var router = express.Router();
var fs = require('fs');

//read file of chore todos
function readCSV(callback) {
  fs.readFile('./data/todoList.csv', function(err, data) {
    if(err) throw err;
    var dataStr = data.toString();
    var array = dataStr.split("\n");
    fs.writeFileSync('./data/todo.json', JSON.stringify(convertToJSON(array), null, 4));
    var temp = convertToJSON(array);
    return callback(temp);
  });
}

//convert array to JSON
function convertToJSON(array) {
  var rows = array.toString();
  rows = rows.split("\r");
  for (var i=1; i<rows.length;i++) {
    rows[i] = rows[i].replace(rows[i][0], "");
  }
  var asJSON = [];
  // get column headers
  var headers = rows[0].split(",");
  
  for (var i=1; i<rows.length-1; i++) {
    var obj = {}
    var currentRow = rows[i].split(",");

    for (var j=0; j<headers.length; j++) {
      obj[headers[j]] = currentRow[j];
    }
    asJSON.push(obj);
  }
  return asJSON;
}

var returnJSON;
readCSV(function(temp) {
  returnJSON=temp;
})

router.get('/', function (req, res, next) {
  res.json(returnJSON);
});

module.exports = router;