node.js serve dir

gistfile1.js

// node.js example
// usage: http://localhost:8080/?path=. will list
// all files under '.'
var Sys = require('sys'),
    Http = require('http'),
    Fs = require('fs'),
    Url = require('url')

function stat(f, if_file, if_dir, if_other) {
  Fs.stat(f, function(err, stat) {
    if (err) if_other()
    else if (stat.isFile()) if_file(f)
    else if (stat.isDirectory()) if_dir(f)
    else if_other()
  })
}

function path_join(x, y) {
  if (x.match(/\/$/))
    return x + y
  else
    return x + "/" + y
}

// We need to stat an array of files
// We don't know when or even what order they execute
// So we keep counts to check when everything is done
function listdir(path, files, cb) {
  var fs = [], 
      ds = [], 
      count = 0

  var if_file = function(f) { 
    count += 1
    fs.push(f)
    if (count == files.length) cb(ds, fs) 
  }

  var if_dir = function(d) { 
    count += 1
    ds.push(d)
    if (count == files.length) cb(ds, fs) 
  }

  var if_other = function() { 
    count += 1
    if (count == files.length) cb(ds, fs) 
  }
  
  files.forEach(function(f) {
    stat(path_join(path, f), if_file, if_dir, if_other)
  })
}

function show(path, dir_cb, file_cb, err_cb) {
  Fs.stat(path, function(err, stat) {
    if (err) {
      err_cb(err)
    } else if (stat.isDirectory()) {
      Fs.readdir(path, function(err, files) {
        if (err) err_cb(err)
        else listdir(path, files, dir_cb)
      })
    } else {
      Fs.readFile(path, function(err, data) {
        if (err) err_cb(err)
        else file_cb(data)
      })
    }
  })
}

function link(response, f) {
  var s = f
  var p = f.lastIndexOf("/", f)
  if (p != -1)
    s = f.substring(p)
  response.write("<a href='/?path=" + f + "'>" + s + "</a><br/>")
}

Http.createServer(function(request, response) {
  var params = Url.parse(request.url, true)
  var path = (params.query && params.query.path) || '.'

  var css = "" +
    "<style>" +
    "html { margin:15px; font-size:22pt; }\n" +
    "a { text-decoration: none; }" +
    "</style>"
  
  var if_dir = function(dirs, files) {
    response.writeHead(200, {'Content-Type': 'text/html'})
    response.write(css)
    link(response, path_join(path, ".."))
    dirs.forEach(function(d) { link(response, d) })
    files.forEach(function(f) { link(response, f) })
    response.end()
  }
  
  var if_file = function(data) {
    response.writeHead(200, {'Content-Type': 'text/plain'})
    response.write(data)
    response.end()
  }
  
  var if_err = function(msg) {
    response.writeHead(200, {'Content-Type': 'text/plain'})
    response.write("an error occurred: " + msg)
    response.end()
  }
  
  show(path, if_dir, if_file, if_err)

}).listen(8080)

My 1st node.js program. Things to note:

• it is blazing fast!
• think callbacks, callbacks, callbacks!
• not sure if I'm doing the "stat an array of files" correctly (maybe there is an easier way?)
• node docs are awesome (didn't have to googling all over the place)