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 bits missing from the core node.js filesystem.
Below is 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)))
// Recursive read dir
async function readDir(dir, allFiles = []) {
const files = (await fs.readdir(dir)).map((file) => path.join(dir, file))
allFiles.push(...files)
await Promise.all(files.map(async (file) => (await fs.stat(file)).isDirectory() && readDir(file, allFiles)))
return allFiles
}
module.exports = {
// Check if file exists
fileExists: fileExists,
// Read file
readFile: promisify(fs.readFile),
// Write file
writeFile: promisify(fs.writeFile),
// Copy file
copyFile: promisify(fs.copyFile),
// Recursively create directory
createDir: mkdirp,
// Read directory file names
readDir: promisify(fs.readdir),
readDirResurvsive
// Recursively delete directory & contents
deleteDir: promisify(rimraf),
}Install mkdirp and rimraf npm packages for deleteDir & createDir
npm install mkdirp rimrafThen 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!
Below is an example of using require('fs').promises instead of promisify from `utils.
/* ./utils/fs.js */
const path = require('path')
const rimraf = require('rimraf')
const { promises, constants } = require('fs')
const { promisify } = require('util')
const fs = promises
const deleteDir = promisify(rimraf)
const deleteFile = (s) => fs.unlink(s).catch((e) => {
if (e.code === 'ENOENT') return // ignore already deleted files
throw e
})
const fileExists = (s) => fs.access(s, constants.F_OK).then(() => true).catch(() => false)
// Recursive read dir
async function readDir(dir, recursive = true, allFiles = []) {
const files = (await fs.readdir(dir)).map((file) => path.join(dir, file))
if (!recursive) return files
allFiles.push(...files)
await Promise.all(files.map(async (file) => {
return (await fs.stat(file)).isDirectory() && readDir(file, recursive, allFiles)
}))
return allFiles
}
async function createDir(directoryPath, recursive = true) {
// ignore errors - throws if the path already exists
return fs.mkdir(directoryPath, { recursive: recursive }).catch((e) => {})
}
async function copyDir(src, dest, recursive = true) {
await createDir(dest, recursive) // Ensure directory exists
const filePaths = await fs.readdir(src)
await Promise.all(filePaths.map(async (item) => {
const srcPath = path.join(src, item)
const destPath = path.join(dest, item)
const itemStat = await fs.lstat(srcPath)
if (itemStat.isFile()) {
return fs.copyFile(srcPath, destPath)
}
// Return early if recursive false
if (!recursive) return
// Copy child directory
return copyDir(srcPath, destPath, recursive)
}))
}
module.exports = {
// Check if file exists
fileExists: fileExists,
// Write file
writeFile: fs.writeFile,
// Read file
readFile: fs.readFile,
// Copy file
copyFile: fs.copyFile,
// Delete file
deleteFile: deleteFile,
// Check if directory exists
directoryExists: fileExists,
// Recursively create directory
createDir: createDir,
// Recursively get file names in dir
readDir: readDir,
// Recursively copy directory
copyDir: copyDir,
// Recursively delete directory & contents
deleteDir: deleteDir,
}Let me know if you have other file system utilities you like to use in the comments below.