just to save

test.js

fs = require('fs');

function getDirectoryFiles(directory, callback) {
  fs.readdir(directory, function(err, files) {
    files.forEach(function(file){
      fs.stat(directory + '/' + file, function(err, stats) {
        if(stats.isFile()) {
          callback(directory + '/' + file);
        }
        if(stats.isDirectory()) {
          getDirectoryFiles(directory + '/' + file, callback);
        }
      });
    });
  });
}

getDirectoryFiles('.', function(file_with_path) {
  console.log(file_with_path);
});