# 6th exercise of learnyounode (using a module to console.log output) - got stuck on stupid stupid thing - \> fewer arguments than expected

**URL:** <https://forum.freecodecamp.org/t/6th-exercise-of-learnyounode-using-a-module-to-console-log-output-got-stuck-on-stupid-stupid-thing-fewer-arguments-than-expected/26725>\
**Category:** General\
**Created:** [August 9, 2016, 8:58pm UTC](https://forum.freecodecamp.org/t/6th-exercise-of-learnyounode-using-a-module-to-console-log-output-got-stuck-on-stupid-stupid-thing-fewer-arguments-than-expected/26725 "2016-08-09T20:58:50Z")\
**Posts on this page:** 7\
**Page:** 1

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**Author:** ![sebastianhew](https://sea3.discourse-cdn.com/freecodecamp/user_avatar/forum.freecodecamp.org/sebastianhew/32/163430_2.png) [@sebastianhew](https://forum.freecodecamp.org/u/sebastianhew)\
**Post date:** [August 9, 2016, 8:58pm UTC](https://forum.freecodecamp.org/t/6th-exercise-of-learnyounode-using-a-module-to-console-log-output-got-stuck-on-stupid-stupid-thing-fewer-arguments-than-expected/26725/1 "2016-08-09T20:58:50Z")

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Hey Campers,

So I’m doing the 6th exercise of learnyounode and i got the correct output in test, but it wanted me to pass more arguments:

> Your submission results compared to the expected:

> ```
> ACTUAL EXPECTED                
> 
> ```
> 
> ────────────────────────────────────────────────────────────────────────────────

> “CHANGELOG.md” == “CHANGELOG.md”  
> “LICENCE.md” == “LICENCE.md”  
> “README.md” == “README.md”  
> “” == “”

> ────────────────────────────────────────────────────────────────────────────────

> ✓ Submission results match expected
> 
> ✓ Additional module file exports a single function
> 
> ✗ Your additional module file [fifth.js] exports a function that takes  
> fewer than three arguments. You must accept a directory, a filter and a  
> callback.
> 
> ```
> # FAIL  
> Your solution to MAKE IT MODULAR didn't pass. Try again! 
> 
> ```

My files look like this:

**The module (fifth.js):**

> var fs = require(‘fs’);

> function callback (err, list) {  
> if (err) return console.error(err);  
> var regexp = “.” + process.argv[3];  
> function goodExt (element) {
> 
> ```
> return element.match(regexp);
> }
> 
> var filtered = list.filter(goodExt);
> for (var i = 0; i < filtered.length; i++) {
> console.log(filtered[i]);
> }
> 
> ```
> 
> }

> module.exports = function exportThat () {  
> fs.readdir(process.argv[2], callback);  
> }

**The main file:**

> var mymodule = require(‘./fifth.js’);  
> mymodule();

Now, i know that i didn’t handle the errors of the fs.readdir yet, that is the second thing i had problems with. But i wanted to cope with that thing first:  
Where do i need to accept those arguments? In `mymodule()` call or in the exportThat() wrapper function? - because i get weird errors when i try both. I’m lost here.

I get that i can access functions from different files with modules, i feel like this exercise is kind of messy.

Any hint appreciated!

**Instructions for the exercise:**

> # LEARN YOU THE NODE.JS FOR MUCH WIN!
> 
> ## MAKE IT MODULAR (Exercise 6 of 13)
> 
> This problem is the same as the previous but introduces the concept of  
> modules. You will need to create two files to solve this.
> 
> Create a program that prints a list of files in a given directory,  
> filtered by the extension of the files. The first argument is the  
> directory name and the second argument is the extension filter. Print the  
> list of files (one file per line) to the console. You must use  
> asynchronous I/O.
> 
> You must write a module file to do most of the work. The module must  
> export a single function that takes three arguments: the directory name,  
> the filename extension string and a callback function, in that order. The  
> filename extension argument must be the same as what was passed to your  
> program. Don’t turn it into a RegExp or prefix with “.” or do anything  
> except pass it to your module where you can do what you need to make your  
> filter work.
> 
> The callback function must be called using the idiomatic node(err, data)  
> convention. This convention stipulates that unless there’s an error, the  
> first argument passed to the callback will be null, and the second will be  
> your data. In this exercise, the data will be your filtered list of files,  
> as an Array. If you receive an error, e.g. from your call to  
> fs.readdir(), the callback must be called with the error, and only the  
> error, as the first argument.
> 
> You must not print directly to the console from your module file, only  
> from your original program.
> 
> In the case of an error bubbling up to your original program file, simply  
> check for it and print an informative message to the console.
> 
> These four things are the contract that your module must follow.
> 
> » Export a single function that takes exactly the arguments described.  
> » Call the callback exactly once with an error or some data as described.  
> » Don’t change anything else, like global variables or stdout.  
> » Handle all the errors that may occur and pass them to the callback.
> 
> The benefit of having a contract is that your module can be used by anyone  
> who expects this contract. So your module could be used by anyone else who  
> does learnyounode, or the verifier, and just work.
> 
> ─────────────────────────────────────────────────────────────────────────────
> 
> ## HINTS
> 
> Create a new module by creating a new file that just contains your  
> directory reading and filtering function. To define a single function  
> export, you assign your function to the module.exports object, overwriting  
> what is already there:
> 
> ```
> module.exports = function (args) { /* ... */ }  
> 
> ```
> 
> Or you can use a named function and assign the name.
> 
> To use your new module in your original program file, use the require()  
> call in the same way that you require(‘fs’) to load the fs module. The  
> only difference is that for local modules must be prefixed with ‘./’. So,  
> if your file is named mymodule.js then:
> 
> ```
> var mymodule = require('./mymodule.js')  
> 
> ```
> 
> The ‘.js’ is optional here and you will often see it omitted.
> 
> You now have the module.exports object in your module assigned to the  
> mymodule variable. Since you are exporting a single function, mymodule is  
> a function you can call!
> 
> Also keep in mind that it is idiomatic to check for errors and do  
> early-returns within callback functions:
> 
> ```
> function bar (callback) {  
> foo(function (err, data) {  
> if (err)  
> return callback(err) // early return  
>    
> // ... no error, continue doing cool things with `data`  
>    
> // all went well, call callback with `null` for the error argument  
>    
> callback(null, data)  
> })  
> }
> 
> ```

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<div class="post-metadata">

**Author:** ![JacksonBates](https://sea3.discourse-cdn.com/freecodecamp/user_avatar/forum.freecodecamp.org/jacksonbates/32/123402_2.png) [@JacksonBates](https://forum.freecodecamp.org/u/JacksonBates)\
**Post date:** [August 9, 2016, 11:19pm UTC](https://forum.freecodecamp.org/t/6th-exercise-of-learnyounode-using-a-module-to-console-log-output-got-stuck-on-stupid-stupid-thing-fewer-arguments-than-expected/26725/2 "2016-08-09T23:19:44Z")

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> [@sebastianhew](#):
>
> module.exports = function exportThat () { fs.readdir(process.argv[2], callback);}

Your current problem is that you exported function currently accepts `0` arguments. The arguments you require your exported function to handle should go in the parentheses:

```javascript
function myFunction(arg1, arg2, arg3) {
  // do stuff
}

```

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<div class="post-metadata">

**Author:** ![sebastianhew](https://sea3.discourse-cdn.com/freecodecamp/user_avatar/forum.freecodecamp.org/sebastianhew/32/163430_2.png) [@sebastianhew](https://forum.freecodecamp.org/u/sebastianhew)\
**Post date:** [August 10, 2016, 12:04am UTC](https://forum.freecodecamp.org/t/6th-exercise-of-learnyounode-using-a-module-to-console-log-output-got-stuck-on-stupid-stupid-thing-fewer-arguments-than-expected/26725/3 "2016-08-10T00:04:03Z")

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Yeah i tried it, but i don’t get it here, why do i need these arguments if i get correct results without them?

and after:

> module.exports = function exportThat (path, dir, cb) {  
> fs.readdir(process.argv[2], callback);  
> }

i get this:

> your additional module file [fifth.js] did not call the callback  
> argument after an error from fs.readdir()

I’m totally lost here, How is it suppose to call the callback after an error from fs.readdir()? Where? readdir doesn’t even have a body,

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<div class="post-metadata">

**Author:** ![JacksonBates](https://sea3.discourse-cdn.com/freecodecamp/user_avatar/forum.freecodecamp.org/jacksonbates/32/123402_2.png) [@JacksonBates](https://forum.freecodecamp.org/u/JacksonBates)\
**Post date:** [August 10, 2016, 1:17am UTC](https://forum.freecodecamp.org/t/6th-exercise-of-learnyounode-using-a-module-to-console-log-output-got-stuck-on-stupid-stupid-thing-fewer-arguments-than-expected/26725/4 "2016-08-10T01:17:08Z")

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where do you assign value to `path, dir, cb`? Currently they don’t mean anything to your function.

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**Author:** ![sebastianhew](https://sea3.discourse-cdn.com/freecodecamp/user_avatar/forum.freecodecamp.org/sebastianhew/32/163430_2.png) [@sebastianhew](https://forum.freecodecamp.org/u/sebastianhew)\
**Post date:** [August 10, 2016, 1:29am UTC](https://forum.freecodecamp.org/t/6th-exercise-of-learnyounode-using-a-module-to-console-log-output-got-stuck-on-stupid-stupid-thing-fewer-arguments-than-expected/26725/5 "2016-08-10T01:29:20Z")

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I see i even got the arguments names not right.

Actually, i watched this walkthrough to clear things out for me. [https://www.youtube.com/watch?v=yHL6mEr-LGY#t=627.926512](https://www.youtube.com/watch?v=yHL6mEr-LGY#t=627.926512)

I guess it was confusing to me for many reasons, one of which was that i already had a callback called ‘callback’ 😃

I didn’t get though , why did i have to return callback(err) if there was an error with readdir, an not just console.error(err) (?)

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<div class="post-metadata">

**Author:** ![JacksonBates](https://sea3.discourse-cdn.com/freecodecamp/user_avatar/forum.freecodecamp.org/jacksonbates/32/123402_2.png) [@JacksonBates](https://forum.freecodecamp.org/u/JacksonBates)\
**Post date:** [August 10, 2016, 1:38am UTC](https://forum.freecodecamp.org/t/6th-exercise-of-learnyounode-using-a-module-to-console-log-output-got-stuck-on-stupid-stupid-thing-fewer-arguments-than-expected/26725/6 "2016-08-10T01:38:08Z")

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I’m not sure 🙂

There 's probably some ‘best practice’ pro reason for doing it that way, but I don’t know what it is!

Make it modular was one of the harder nodeschool lessons for me to complete, too, but making modular scripts is a godsend when you get into the backend API projects.

Congrats on moving on 🙂

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**Author:** ![jwilkins.oboe](https://sea3.discourse-cdn.com/freecodecamp/user_avatar/forum.freecodecamp.org/jwilkins.oboe/32/179497_2.png) [@jwilkins.oboe](https://forum.freecodecamp.org/u/jwilkins.oboe)\
**Post date:** [January 16, 2021, 4:41am UTC](https://forum.freecodecamp.org/t/6th-exercise-of-learnyounode-using-a-module-to-console-log-output-got-stuck-on-stupid-stupid-thing-fewer-arguments-than-expected/26725/7 "2021-01-16T04:41:07Z")

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Closed on January 16, 2021, 4:41am UTC