Solutions to Learnyounode ---> Make it Modular

program.js

'use strict'
var readFile = require('./readFile.js')

var file = process.argv[2]
var filtered = process.argv[3]

readFile(file, filtered, function(err, list) {
  if (err) {
      return console.log(err)
  }
  list.forEach(function (list) {
      console.log(list)
    })
  })

  var readFile = require('./readFile.js')

  var file = process.argv[2]
  var filtered = process.argv[3]

readFile(file, filtered, function(err, list) {
  if (err) {
    console.log(err)
  }
  list.forEach(function(file) {
    console.log(file)
  })
})

readFile.js

var fs = require('fs')
var path = require('path')

module.exports = function (dir, stringFind, callback) {
  fs.readdir(dir, function (err, list) {
    if (err) {
      return callback(err)
    }

    list = list.filter(function (file) {
      return path.extname(file) === '.' + stringFind
    })

    callback(null, list)
  })
}