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David Wells
David Wells

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Promisified node.js file system utilities

Originally published on

Node introduced the promisify utilities in back in version 8.

Using promisify you can use the node.js file system utilities with async/await and promises.

There are a couple of bits missing from the core node.js filesystem.

Below are the promisified file system calls I use a bunch in projects.

I've added createDir, fileExists, and deleteDir to smooth over some of the core fs methods that can be a little awkward to work with.

/* ./utils/fs.js */
const fs = require('fs')
const mkdirp = require('mkdirp')
const rimraf = require('rimraf')
const { promisify } = require('util')

const fileExists = (s) => new Promise(r => fs.access(s, fs.F_OK, e => r(!e)))

module.exports = {
  // Check if file exists
  fileExists: fileExists,
  // Read file
  readFile: promisify(fs.readFile),
  // Write file
  writeFile: promisify(fs.writeFile),
  // Recursively create directory
  createDir: mkdirp,
  // Read directory file names
  readDir: promisify(fs.readdir),
  // Recursively delete directory & contents
  deleteDir: promisify(rimraf),

Install mkdirp and rimraf npm packages for deleteDir & createDir

npm install mkdirp rimraf

Then you can use it in your project

const path = require('path')
const { fileExists, readFile } = require('./utils/fs')

async function doIt(filePath) {
  const exists = await fileExists(filePath)  
  let contents
  if (exists) {
    contents = await readFile(filePath)
  return contents

const file = path.resolve('foo-bar.json')
doIt(file).then((contents) => {
  console.log('Yay 🎉', contents)

Hope this helps!

Let me know if you have other file system utilities you like to use in the comments below.

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