a_functions_only.js

var fs = require('fs')

var DataCollector = function(arr) {
  this.setFiles(arr)
}

DataCollector.prototype = {
  setFiles: function(arr) {
    this.files = arr
  }
  , getFilenameLengths: function() {
    var sizes = {}

    this.files.forEach(function(filename, index) {
      sizes[filename] = filename.length
    })

    return sizes
  }

  , getFileData: function() {
    var fileData = {}

    this.files.forEach(function(filename, index) {

      fs.readFile(filename, function(err, data) {
        fileData[filename] = data
      })

    })

    return fileData
  }
}

var array = ["foo.json", "bar.json", "baz.json"]

var dc1 = new DataCollector(array)
console.log(dc1.getFilenameLengths()) // yay!

var dc2 = new DataCollector(array)
console.log(dc2.getFileData())  // womp womp

b_functions_and_blocks.js

var fs = require('fs')

var DataCollector = function(arr) {
  this.setFiles(arr)
}

DataCollector.prototype = {
  setFiles: function(arr) {
    this.files = arr
  }
  , getFilenameLengths: function() {
    var sizes = {}

    this.files.forEach({|filename, index|
      sizes[filename] = filename.length
    })

    return sizes
  }

  , getFileData: function() {
    var fileData = {}

    this.files.forEach({|filename, index|

      fs.readFile(filename, {|err, data|
        fileData[filename] = data
      })

    })

    return fileData
  }
}

var array = ["foo.json", "bar.json", "baz.json"]

var dc1 = new DataCollector(array)
console.log(dc1.getFilenameLengths()) // yay!

var dc2 = new DataCollector(array)
console.log(dc2.getFileData())  // still doesn't work

c_functions_with_this_and_return.js

var fs = require('fs')

var DataCollector = function(arr) {
  this.setFiles(arr)
}

DataCollector.prototype = {
  setFiles: function(arr) {
    this.files = arr
  }
  , getFilenameLength: function(filename) {
    return filename.length;
  }
  , getAllFilenameLengths: function() {
    var sizes = {}

    this.files.forEach(function(filename, index) {
      sizes[filename] = this.getFilenameLength(filename);
    })

    return sizes
  }

  , getFileData: function(filename) {
    fs.readFile(filename, function(err, data) {
      if(err) throw err  // useless

      return data; // yeah right
    })
  }
  , getAllFileData: function() {
    var fileData = {}

    this.files.forEach(function(filename, index) {
      fileData[filename] = this.getFileData(filename) // where's your callback?
    })

    return fileData
  }
}

var array = ["foo.json", "bar.json", "baz.json"]
var dc1 = new DataCollector(array)

console.log(dc1.getAllFilenameLengths()) // uh oh, we broke this!

var dc2 = new DataCollector(array)
console.log(dc2.getFileData('bar.json')) // nope
console.log(dc2.getAllFileData())  // nada

d_less_functions_more_blocks.js

var fs = require('fs')

var DataCollector = function(arr) {
  this.setFiles(arr)
}

DataCollector.prototype = {
  setFiles: function(arr) {
    this.files = arr
  }
  , getFilenameLength: function(index) {
    var filename = this.files[index];
    return filename.length;
  }
  , getAllFilenameLengths: function() {
    var sizes = {}

    for(var i = 0; i < this.files.length; i++) {
      var filename = this.files[i] // hoisted var, no real harm here
      sizes[filename] = this.getFilenameLength(i) // double lookup, also not terrible
    }

    return sizes
  }

  , getFileData: function(filename) {
    fs.readFile(filename, {|err, data|
      if(err) throw err  // maybe?

      return data // hopefully?
    })
  }
  , getAllFileData: function() {
    var fileData = {}

    for(var i = 0; i < this.files.length; i++) {
      var filename = this.files[i]
      fileData[filename] = this.getFileData(filename) // this surely works right?
    }

    return fileData
  }
}

var array = ["foo.json", "bar.json", "baz.json"]
var dc1 = new DataCollector(array)

console.log(dc1.getAllFilenameLengths()) // yay (again)!

var dc2 = new DataCollector(array)
console.log(dc2.getFileData('bar.json')) // probably not
console.log(dc2.getAllFileData())  // not likely

e_just_js_the_hard_way.js

var fs = require('fs')

var DataCollector = function(arr) {
  this.setFiles(arr)
}

DataCollector.prototype = {
  setFiles: function(arr) {
    this.files = arr
  }
  , getFilenameLength: function(index) {
    return this.files[i].length
  }
  , getAllFilenameLengths: function() {
    var sizes = {}
      , filename = null

    for(var i = 0; i < this.files.length; i++) {
      filename = this.files[i]
      sizes[filename] = filename.length
    }

    return sizes
  }

  //, getFileData: function(filename, callback) {
  //  fs.readFile(filename, callback)
  //}
  // better yet
  , getFileData: fs.readFile
  , getAllFileData: function(callback) {
    var self = this
      , fileData = {}
      , num = this.files.length

    this.files.forEach(function(filename, index) {

      self.getFileData(filename, function(err, data) {
        num--
        if(!err) {
          fileData[filename] = data
        }

        if(err || num === 0) callback(err, fileData)
      })

    })
  }
}

var array = ["foo.json", "bar.json", "baz.json"]
var dc1 = new DataCollector(array)

console.log(dc1.getAllFilenameLengths()) // yay!

var dc2 = new DataCollector(array)
// works but you have to handle the error
dc2.getFileData('bar.json', function(err, data) {
  console.log(data);
})

// works but same problem
dc2.getAllFileData(function(err, data) {
  console.log(data);
})

f_moar_blocks.js

var fs = require('fs')

var DataCollector = function(arr) {
  this.setFiles(arr)
}

DataCollector.prototype = {
  setFiles: function(arr) {
    this.files = arr
  }
  , getFilenameLength: function(index) {
    return this.files[i].length
  }
  , getAllFilenameLengths: function() {
    var sizes = {}
      , filename = null

    for(var i = 0; i < this.files.length; i++) {
      filename = this.files[i]
      sizes[filename] = filename.length
    }

    return sizes
  }

  //, getFileData: function(filename, callback) {
  //  fs.readFile(filename, callback)
  //}
  // better yet
  , getFileData: fs.readFile
  , getAllFileData: function(callback) {
    var fileData = {}
      , num = this.files.length

    this.files.forEach({|filename, index|

      this.getFileData(filename, {|err, data|
        num--
        if(!err) {
          fileData[filename] = data
        }

        if(err || num === 0) callback(err, fileData)
      })

    })
  }
}

var array = ["foo.json", "bar.json", "baz.json"]
var dc1 = new DataCollector(array)

console.log(dc1.getAllFilenameLengths()) // yay!

var dc2 = new DataCollector(array)
// works but you have to handle the error
dc2.getFileData('bar.json', {|err, data|
  console.log(data);
})

// works but same problem
dc2.getAllFileData({|err, data|
  console.log(data);
})

g_smarter_not_harder.js

var fs = require('fs')
  , memoize = require('functools').memoize
  , async = requie('async')

var DataCollector = function(arr) {
  this.files = arr
}

DataCollector.prototype = {
  , getAllFilenameLengths: memoize(function() {
    var sizes = {}

    this.files.forEach(function(filename) {
      sizes[filename] = filename.length
    })

    return sizes
  })
  , getFileData: memoize.async(fs.readFile)
  , getAllFileData: memoize.async(function(callback) {
    var fileData = {}

    async.collect(this.files, this.getFileData, {|filename, data|
      fileData[filename] = data
    }).then(function(err) {
      callback(err, fileData)
    })
  })
}

var array = ["foo.json", "bar.json", "baz.json"]
var dc1 = new DataCollector(array)

console.log(dc1.getAllFilenameLengths()) // yay!

var dc2 = new DataCollector(array)
dc2.getAllFileData(console.log)