Node.js遍历目录（异步）

expand_dir.js

var fs = require('fs');
var path = require('path');
var THREAD = require('os').cpus().length;

var expand = function (file, callback) {
  fs.stat(file, function (err, stats) {
    if (err)
      return callback(err);
    if (!stats.isDirectory()) {
      return callback(null, stats.size);
    } else {
      fs.readdir(file, function (err, files) {
        if (err)
          return callback(err);
        for (var i = 0, len = files.length; i < len; i++)
          files[i] = path.join(file, files[i]);
        var size = 0;
        var finish = 0;
        var threadFinish = function () {
          finish++;
          if (finish >= THREAD)
            return callback(null, size);
        };
        var next = function () {
          var f = files.pop();
          if (!f)
            return threadFinish();
          expand(f, function (err, s) {
            if (err)
              return callback(err);
            size += s;
            next();
          });
        };
        for (var i = 0; i < THREAD; i++)
          next();
      });
    }
  });
};

var ts = new Date();
expand('d:\\', function (err, size) {
  if (err)
    console.log(err.stack);
  var te = new Date();
  console.log('Size: ' + size);
  console.log('Spent: ' + (te - ts));
});