walk_dir.js

var fs = require('fs');

var methods = {
    walk: function (dir, validation_function, cb) {
        if (arguments.length === 2) {
            cb = validation_function;
            validation_function = null;
        }

        var results = [];
        fs.readdir(dir, function (err, list) {
            if (err) { return cb(err); }

            var pending = list.length;

            if (!pending) { return cb(null, results); }

            list.forEach(function (file) {
                file = dir + '/' + file;
                fs.stat(file, function (err, stat) {
                    if (stat && stat.isDirectory()) {
                        methods.walk(file, validation_function, function (err, res) {
                            results = results.concat(res);
                            if (!--pending) { cb(null, results); }
                        });
                    } else {
                        if (typeof validation_function === 'function') {
                            if (validation_function(file)) {
                                results.push(file);
                            }
                        } else {
                            results.push(file);
                        }

                        if (!--pending) { cb(null, results); }
                    }
                });
            });
        });
    }
};

module.exports = methods;