learnyounode - filteredLS.js

var fs = require('fs'); // require is a special function provided by node
var path = require('path'); //require path function provided by node

var pathName = process.argv[2]; //full path name passed in as array
var ext = process.argv[3]; //extenstion we need to filter array by passed in as string

var filteredList = undefined; //Global variable. We do not know the file type, so I set to undefined.

function filteredLS(callback) {
  fs.readdir(pathName, function doneReading(err, files) {  //Async node call. Pass in pathname and async function
  	for (i = 0; i < files.length; i++) { //cycle through all of the filenames in the array
  		if (path.extname(files[i]) === '.' + ext) {  //Check if the file name is equal to our extenstion filter with the node path.extname function
  			filteredList = files[i]; //If yes, set filtered list item to this value
  			callback(); //Call the async callback function
  		}
  	}
  })
}

function logMyAnswer() { //Callback function
  console.log(filteredList); //console log the filtered item
}

filteredLS(logMyAnswer);  



// Here's the official solution in case you want to compare notes:

// ────────────────────────────────────────────────────────────────────────────────
//     var fs = require('fs')
//     var path = require('path')
    
//     fs.readdir(process.argv[2], function (err, list) {
//       list.forEach(function (file) {
//         if (path.extname(file) === '.' + process.argv[3])
//           console.log(file)
//       })
//     })