nodeschool learnyounode node.js module FILTER LS exercise

Question

Below is the exercise 5 of nodeschool learnyounode module

Create a program that prints a list of files in a given directory, filtered by he extension of the files. You w

Answer 1

Your problem is just a typo. You're doing this:

    if(ext == ext){ // you're comparing the same variable
      console.log(filename);
    }

, but you should be doing this:

    if(ext === ext1){ // try to use '==='
      console.log(filename);
    }

Other thing: they're not considering the . of .txt in the input, so you have to append this in your variable ext1 because .extname(file) returns the extention with the .:

var ext1 = '.' + process.argv[3];

Answer 2

The solution given uses the path module from Node JS package. The solution below doesn't use path, instead relies on simple deconstruction of given filename and using the parts needed.

-Import fs module

    var fs = require('fs');

-Extract the path and ext name required from cmd line

    let filePath = process.argv[2];
    let extName = process.argv[3];

-Use (readdir) method to read the contents of a directory. The names of files inside the directory will be returned in the form of an array.

    fs.readdir(filePath, 'utf-8', function(err, data) {
      if (err) throw err;

      data.forEach(element => {

-Take each element and split it into filename and extension name

      let temp = element.split('.');
      let tempSplit = temp[1];
      if(tempSplit === extName) {
        console.log(temp[0] + '.' + temp[1]);
      }
    });

Whole code for reference:

    var fs = require('fs');

    let filePath = process.argv[2];
    let extName = process.argv[3];

    fs.readdir(filePath, 'utf-8', function(err, data) {
      if (err) throw err;

      data.forEach(element => {
      let temp = element.split('.');
      let tempSplit = temp[1];
      if(tempSplit === extName) {
        console.log(temp[0] + '.' + temp[1]);
      }
    });

Answer 3

Heres what I came up with, if you want other solutions to problem:

var fs = require('fs');
var path = process.argv[2]; //first argument
var extension = process.argv[3]; //second argument
var re = new RegExp("."+extension, "g"); //a regexp that matches every string that begins with a dot and is followed by the extension, i.e. .txt

fs.readdir(path, function callback(err, list){ //read the directory
  if (!err) { //if no errors occur run next funtion
    list.forEach(function(val) { //take the list and check every value with the statement below
      if(re.test(val)) { //if the .test() rexexp-function does not match it will return a false, if it does it will return true
        console.log(val); //if it matches console log the value
      }
    });
  }
});

Answer 4

You can try this code to solve this exercise :

var fs = require('fs');
    function endsWith(str, suffix) {
        var s = str.slice(str.length - suffix.length - 1);
        if (s == "." + suffix)
            return true;
        else
            return false;
};


fs.readdir(process.argv[2], function (err, list) {
    if (process.argv[3]) {
        for (var i = 0; i < list.length; i++) {
            if (endsWith(list[i], process.argv[3]))
                console.log(list[i]);
        }
    }
});

Answer 5

Here's the official solution:

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)
  })
})

Answer 6

The only thing missing in your code is the concatenation of '.' before the file extension type.

var extension = '.'+ process.argv[3];

You can then do the comparison and printing.