nodeschool.io 5

~~ FILTERED LS ~~

Create a program that prints a list of files in a given directory,
filtered by the extension of the files. You will be provided a
directory name as the first argument to your program (e.g.
'/path/to/dir/') and a file extension to filter by as the second
argument.

For example, if you get 'txt' as the second argument then you will
need to filter the list to only files that end with .txt.

The list of files should be printed to the console, one file per line.
You must use asynchronous I/O.

----------------------------------------------------------------------
HINTS:

The `fs.readdir()` method takes a pathname as its first argument and a
callback as its second. The callback signature is:

function (err, list) { ... }

where `list` is an array of filename strings.

Documentation on the `fs` module can be found by pointing your browser
here:
C:\Users\dzhang\AppData\Roaming\npm\node_modules\learnyounode\node_api
tml

You may also find the standard JavaScript `RegExp` class helpful here.

我写的：

var fs = require('fs');
var patt1=new RegExp("\.dat");
var fliter = fs.readdir(process.argv[2],function(err,list){
    for(var i = 0 ; i < list.length ; i++){
 
        if(list[i].split(".").length > 1){
            if(patt1.exec(list[i])){
                console.log(list[i]);
            }
        }
    }
})

网站的答案：

  var fs = require('fs')
  var regex = new RegExp('\\.' + process.argv[3] + '$')
 
  fs.readdir(process.argv[2], function (err, list) {
    list.forEach(function (file) {
      if (regex.test(file))
        console.log(file)
    })
  })