var request = require('request');
var parseString = require('xml2js').parseString;
var fs = require('fs');

//Some needed variables

streamInterval = setInterval(function() {
      request.get(addr, function (error, response, body) {
      if (!error && response.statusCode == 200) {
        parseString(body,{ explicitArray : false, ignoreAttrs : true }, function (err, result) {
            var jsonResult = JSON.stringify(result);
            var result = JSON.parse(jsonResult);

            fs.writeFile(outputDeparts, JSON.stringify(result, null, 4), function(err) {
                if(err) {
                  console.log(err);
                }
            });

        });
      }else{
        console.log("An error occured : " + response.statusCode);
      }
    }).auth(LOGIN,PASS,true);
  }, 30000);

var fs = require('fs');

//Some needed variables


fs.watch(outputDeparts, (eventType, filename) => {
  console.log(`event type is: ${eventType}`);
  if (filename) {
    console.log(`filename provided: ${filename}`);
    fs.readFile(outputDeparts, 'utf8', function (err, data) {
      if (err){
        throw err;
      }else{
        console.log('start parsing');
        console.log(data);
        var result = JSON.parse(data);
        var departs = result["passages"]["train"];
        console.log(`next train [${departs[0]["num"]}] at : ${departs[0]["date"]}`);
      }
    });
  } else {
    console.log('filename not provided');
  }
});

undefined:1

SyntaxError: Unexpected end of input
    at Object.parse (native)
    at /Users/adobe/Documents/workspace/playWithNode/watchFile.js:17:23
    at tryToString (fs.js:414:3)
    at FSReqWrap.readFileAfterClose [as oncomplete] (fs.js:401:12)