javascript - Modules and Node.js -

i'm trying learn node.js basics doing learnyounode lessons. stuck @ make modular chapter.

i don't know if i'm allowed paste content here, roughly, asked create module filter file names in directory following specified extension.

here i've done far:

var module = require('module');  module(process.argv[2], process.argv[3], function (err, data){   if(err){     console.log("error");   }   else{     console.log(data);   } }); 

module.js:

var fs = require('fs'); var path = require('path');  module.exports = function (dir, ext, callback){   fs.readdir(dir, function (err, files){     if(err){       callback(err);     }     else {       var array = '';       for(var i=0; i<files.length; i++){         if(path.extname(files[i]) === '.'+ext){          array+=files[i]+"\n";         }       }       callback(null, array);     }   }); } 

i following error:

module.js:27   this.id = id;           ^  typeerror: cannot set property 'id' of undefined     @ module (module.js:27:11)     @ object.<anonymous> (/home/maxence/documents/node.js/learnyounode/mim/mim.js:3:1)     @ module._compile (module.js:397:26)     @ object.module._extensions..js (module.js:404:10)     @ module.load (module.js:343:32)     @ function.module._load (module.js:300:12)     @ module.require (module.js:353:17)     @ require (internal/module.js:12:17)     @ object.<anonymous> (/usr/local/lib/node_modules/learnyounode/node_modules/workshopper-wrappedexec/exec-wrap.js:87:3)     @ module._compile (module.js:397:26) 

my guess i've not declared variable correctly somewhere in code can't manage find it. call of module correct?

best regards, mm

edit : gnerkus said, there should './module' instead of 'module'. here working code:

var module = require('./module');  module(process.argv[2], process.argv[3], function (err, data){   if(err){     console.log("error");   }   else{     console.log(data);   } }); 

module.js:

var fs = require('fs'); var path = require('path');  module.exports = function (dir, ext, callback){   fs.readdir(dir, function (err, files){     if(err){       callback(err);     }     else {       var array = '';       for(var i=0; i<files.length; i++){         if(path.extname(files[i]) === '.'+ext){          array+=files[i]+"\n";         }       }       callback(null, array);     }   }); } 

edit 2: seems version preferred:

var module = require('./module');  module(process.argv[2], process.argv[3], function (err, data){   if(err){     console.log("error");   }   else{     for(var i=0; i<data.length; i++){        console.log(data[i]);     }   } }); 

module.js:

var fs = require('fs'); var path = require('path');  module.exports = function (dir, ext, callback){   fs.readdir(dir, function (err, files){     if(err){       callback(err);     }     else {       var array = [];       for(var i=0; i<files.length; i++){         if(path.extname(files[i]) === ('.'+ext)){          array.push(files[i]);         }       }       callback(null, array);     }   }); } 

both correct, second version required complete chapter.

the error occurs because you're requiring node module , not custom module. nodejs documentation:

if module identifier passed require() not native module, , not begin '/', '../', or './', node.js starts @ parent directory of current module, , adds /node_modules, , attempts load module location. node not append node_modules path ending in node_modules.

solution.js

var mymodule = require('./module'); // rest of code.