Node.js find files recursively

findFilesRecursively.js

const assert = require("assert");
const fs = require("fs");
const path = require("path");

function findFilesRecursively(pathToDir) {
  assert(typeof pathToDir === "string");

  return fs.readdirSync(pathToDir).map(filename => {
    const fullpath = path.join(pathToDir, filename);
    if (isFile(fullpath)) {
      return [fullpath];
    } else if (isDirectory(fullpath)) {
      return findFilesRecursively(fullpath);
    }
    return [];
  }).reduce((files, current) =>
    files.concat(current)
  , []);
}

function isDirectory(pathToDir) {
  assert(typeof pathToDir === "string");

  try {
    const stats = fs.statSync(pathToDir);
    return stats.isDirectory();
  } catch (err) {
    return false;
  }
}

function isFile(pathToFile) {
  assert(typeof pathToFile === "string");

  try {
    const stats = fs.statSync(pathToFile);
    return stats.isFile();
  } catch (err) {
    return false;
  }
}