Simple nodejs callback example with fs.readFile

Question

I\'m trying to learn async programming and was struggling with lesson 4 of nodeschool.io with the implementation of an async io with callbacks.

Basically, I\'m trying to

Answer 1

Trying to treat errors as well. Not sure, if it is better to propagate the error in the last callback. I think the functionality is quite basic, but anyway I am propagating errors.

I would also say is more correct to delegate the split in the last callback rather than passing it through an argument or similar.

var fs = require('fs');
var myfile = process.argv[2];



function solution(file, callback){
fs.readFile(file, "utf-8", function (err, data) {
    if (err) callback(err);
    callback(null, data)
});
}

function mycallback(err,data){
  if (err) callback(err) console.error(err);
  return data.split('\n').length-1);
}

solution(myfile,mycallback)