Question

我正在完成nodeschool.io learnyounode练习＃6，makeitmodular。

我得到了正确的结果，但是对于我不熟悉的一段代码仍然存在错误。任何帮助都会很棒。

以下是结果和错误：

Your submission results compared to the expected:

                 ACTUAL                                 EXPECTED                
────────────────────────────────────────────────────────────────────────────────

   "CHANGELOG.md"                      ==    "CHANGELOG.md"                     
   "LICENCE.md"                        ==    "LICENCE.md"                       
   "README.md"                         ==    "README.md"                        
   ""                                  ==    ""                                 

────────────────────────────────────────────────────────────────────────────────

/usr/local/lib/node_modules/learnyounode/node_modules/workshopper-exercise/exercise.js:182
    processors[i].call(self, mode, function (err, pass) {
                 ^

TypeError: Cannot read property 'call' of undefined
    at next (/usr/local/lib/node_modules/learnyounode/node_modules/workshopper-exercise/exercise.js:182:18)
    at /usr/local/lib/node_modules/learnyounode/node_modules/workshopper-exercise/exercise.js:189:7
    at callback (/usr/local/lib/node_modules/learnyounode/exercises/make_it_modular/verify.js:26:15)
    at modFileError (/usr/local/lib/node_modules/learnyounode/exercises/make_it_modular/verify.js:31:5)
    at /usr/local/lib/node_modules/learnyounode/exercises/make_it_modular/verify.js:119:18
    at /Users/Olly/workspace/learnyounode/mymodule.js:13:13
    at Array.forEach (native)
    at /Users/Olly/workspace/learnyounode/mymodule.js:11:9
    at FSReqWrap.oncomplete (fs.js:82:15)

我的makeitmodular.js文件是：

var dir = process.argv[2];
var filter = process.argv[3];
var mymodule = require('./mymodule.js')


mymodule (dir,filter, function (err, data) {
    if (err) {
        console.log("There was an error")
    }
    else {
        console.log(data)
        }    

})

我的module.js文件是：

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

module.exports = function(dir, filter, callback) {

    fs.readdir(dir, function (err, list) {
        if (err) {
            return callback(err)
        }
        else {
            list.forEach( function(file) {
                if ( path.extname(file) === '.' + filter ) {
                    return callback(null, file)             
                }
            })
        }
    })




};

Answer 1

我认为问题在于它希望您使用已过滤列表的数组调用一次回调函数，而不是每次都在forEach方法中调用。

----------这是我的解决方案，以防你要比较笔记----------

我的makeitmodular.js文件是：

var path = require('path');
var mymodule = require('./mymodule');
var dir = process.argv[2];
var filterExtension = process.argv[3];

var callback = function (err, list) {
    if (err) throw err;
    list.forEach(function (file) {
        console.log(file);
    })
}

mymodule(dir, filterExtension, callback);

我的module.js文件是：

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

module.exports = function (directory, extension, callback) {
    fs.readdir(directory, function (err, list) {
        if (err) return callback(err);
        else {
            list = list.filter(function (file) {
                if(path.extname(file) === '.' + extension) return true;
            })
            return callback(null, list);
        }
    })
}

Answer 2

我同意挑战的措辞可以更清楚。这是代码的另一个版本，以防其他人感兴趣：

filter.js：

const path = process.argv[2]
const fileType = process.argv[3]
const readNewlines = require('./readNewlines')

readNewlines(path, fileType, function(err, result) {
    if(err) return err;
    console.log(result.join('\n'));
})

readNewlines.js：

const fs = require('fs')

readNewlines = function(path, fileType, callback) {
    fs.readdir(path, function(err, result) {
        if(err) return callback(err);

        const res = result.filter(function(fileName) {
            return (fileName.indexOf('.'+fileType) !== -1);
        }).map(fileName => {
            return fileName
        })

        return callback(null, res);
    })
}

module.exports = readNewlines;

Answer 3

我只用ES6编写了一个更清晰的答案，我同意其余的这个挑战有点不清楚。

program.js

const myModule = require('./myModule.js');
const dir = process.argv[2];
const ext = process.argv[3];

myModule(dir, ext, (err, list) => {
    return err ? console.error('There is an error:', err) : 
    console.log(list.join('\n'));
});

myModule.js

const fs = require('fs');
const path = require('path');

const myModule = (dir, ext, cb) => {
    fs.readdir(dir, (err, list) => {
        return err ? cb(err) : cb(null, list.filter(file => 
        path.extname(file) === `.${ext}`));
    });
};

module.exports = myModule;

Answer 4

这是我提供的代码，可为您提供确切的预期结果，并将匿名函数附加到导出对象：

filtered.js（模块）

module.exports = function (dir, ext, callback) {
  var fs = require('fs');
  var path = require('path');
  var filteredList = [];
  var currentFile;
  var currentExt;
  var x;

  fs.readdir(dir, function (err, list) {
    if (err) {
      return callback(err);
    }

    for (x in list) {
      currentFile = list[x];
      currentExt = path.extname(currentFile);

      if (currentExt === '.' + ext) {
        filteredList.push(currentFile);
      }
    }
    return callback(null, filteredList);
  });
};

make-it-modular.js（程序）

var filter = require('./filtered');
var file = process.argv[2];
var ext = process.argv[3];

var callback = function (err, list) {  
  for (x in list) {
    console.log(list[x]);
  }
}

filter(file, ext, callback);

Answer 5

我想出了一个更简洁的解决方案：

mymodule.js

const path = require('path');
const fs = require('fs');

module.exports = function (dir, ext, cb) {
    fs.readdir(dir, (err, data) => {
        if(err) return cb(err);
        
        cb(
            null,
            data.filter(file => path.extname(file) === `.${ext}`)
        );
    });
}

make-it-modular.js

const mod = require('./mymodule');

const dir = process.argv[2];
const ext = process.argv[3];

mod(dir, ext, (err, data) => {
    if(err) console.log(err);
    data.forEach(element => console.log(element));
});

Learnyounode＃6使其模块化：正确的结果和同时抛出错误？

5 个答案:

filtered.js（模块）

make-it-modular.js（程序）