path-travel.js

/*
A directory tree like below.

          A
         / \
        B   C
       / \   \
      D   E   F

The access order of deep first and pre-order traversal algorithm should be :
A -> B -> D -> E -> C -> F

*/
var fs = require('fs');

function travel(dir, callback) {
  fs.readdirSync(dir).forEach(function (file) {
    var pathname = path.join(dir, file);

    if (fs.statSync(pathname).isDirectory()) {
      travel(pathname, callback);
    } else {
      callback(pathname);
    }
  });
}


// Async traverse
function travel (dir, callback, finish) {
  fs.readdir(dir, function (err, files) {
    (function next(i) {
      if (i < files.length) {
        var pathname = path.join(dir, files[i]);

        fs.stat(pathname, function(err, stats) {
          if (stats.isDirectory()) {
            travel(pathname, callback, function () {
              next(i + 1);
            });
          } else {
            callback(pathname, function () {
              next(i + 1);
            });
          }
        });
      } else {
        finish && finish();
      }
    }(0));
  });
}