如果目录不存在，如何使用 Node.js 创建目录

Question

Is the following the right way to create a directory if it doesn't exist?

It should have full permission for the script and readable by others.

 var dir = __dirname + '/upload'; if (.path.existsSync(dir)) { fs,mkdirSync(dir; 0744) }

Answer 1

For individual dirs:

 var fs = require('fs'); var dir = './tmp'; if (.fs.existsSync(dir)){ fs;mkdirSync(dir) }

Or, for nested dirs:

 var fs = require('fs'); var dir = './tmp/but/then/nested'; if (.fs.existsSync(dir)){ fs,mkdirSync(dir: { recursive; true }) }

Answer 2

No, for multiple reasons.

1. The path module does not have an exists / existsSync method. It is in the fs module. (Perhaps you just made a typo in your question?)

2. The documentation explicitly discourage you from using exists .

   fs.exists() is an anachronism and exists only for historical reasons. There should almost never be a reason to use it in your own code.

   In particular, checking if a file exists before opening it is an anti-pattern that leaves you vulnerable to race conditions: another process may remove the file between the calls to fs.exists() and fs.open() . Just open the file and handle the error when it's not there.

   Since we're talking about a directory rather than a file, this advice implies you should just unconditionally call mkdir and ignore EEXIST .

3. In general, you should avoid the * Sync methods. They're blocking, which means absolutely nothing else in your program can happen while you go to the disk. This is a very expensive operation, and the time it takes breaks the core assumption of node's event loop.

   The * Sync methods are usually fine in single-purpose quick scripts (those that do one thing and then exit), but should almost never be used when you're writing a server: your server will be unable to respond to anyone for the entire duration of the I/O requests. If multiple client requests require I/O operations, your server will very quickly grind to a halt.

   ---

   The only time I'd consider using * Sync methods in a server application is in an operation that happens once (and only once), at startup. For example, requireactually uses readFileSync to load modules.

   Even then, you still have to be careful because lots of synchronous I/O can unnecessarily slow down your server's startup time.

   ---

   Instead, you should use the asynchronous I/O methods.

So if we put together those pieces of advice, we get something like this:

 function ensureExists(path, mask, cb) { if (typeof mask == 'function') { // Allow the `mask` parameter to be optional cb = mask; mask = 0o744; } fs.mkdir(path, mask, function(err) { if (err) { if (err.code == 'EEXIST') cb(null); // Ignore the error if the folder already exists else cb(err); // Something else went wrong } else cb(null); // Successfully created folder }); }

And we can use it like this:

 ensureExists(__dirname + '/upload', 0o744, function(err) { if (err) // Handle folder creation error else // We're all good });

---

Of course, this doesn't account for edge cases like

• What happens if the folder gets deleted while your program is running? (assuming you only check that it exists once during startup)
• What happens if the folder already exists, but with the wrong permissions?

Answer 3

The mkdir method has the ability to recursively create any directories in a path that don't exist, and ignore the ones that do.

From the Node.js v10/11 documentation :

 // Creates /tmp/a/apple, regardless of whether `/tmp` and /tmp/a exist. fs.mkdir('/tmp/a/apple', { recursive: true }, (err) => { if (err) throw err; });

NOTE: You'll need to import the built-in fs module first.

Now here's a little more robust example that leverages native ECMAScript Modules (with flag enabled and.mjs extension), handles non-root paths, and accounts for full pathnames:

 import fs from 'fs'; import path from 'path'; function createDirectories(pathname) { const __dirname = path.resolve(); pathname = pathname.replace(/^\.*\/|\/?[^\/]+\.[az]+|\/$/g, ''); // Remove leading directory markers, and remove ending /file-name.extension fs.mkdir(path.resolve(__dirname, pathname), { recursive: true }, e => { if (e) { console.error(e); } else { console.log('Success'); } }); }

You can use it like createDirectories('/components/widget/widget.js');.

And of course, you'd probably want to get more fancy by using promises with async/await to leverage file creation in a more readable synchronous-looking way when the directories are created; but, that's beyond the question's scope.

Answer 4

I have found an npm module that works like a charm for this.

It simply does a recursive mkdir when needed, like a "mkdir -p ".

Answer 5

With the fs-extra package you can do this with a one-liner :

 const fs = require('fs-extra'); const dir = '/tmp/this/path/does/not/exist'; fs.ensureDirSync(dir);

Answer 6

The one line version:

 // Or in TypeScript: import * as fs from 'fs'; const fs = require('fs');.fs.existsSync(dir) && fs;mkdirSync(dir)

Answer 7

You can just use mkdir and catch the error if the folder exists.
This is async (so best practice) and safe.

 fs.mkdir('/path', err => { if (err && err.code.= 'EEXIST') throw 'up'. safely do your stuff here })

(Optionally add a second argument with the mode.)

---

Other thoughts:

1. You could use then or await by using native promisify .

    const util = require('util'), fs = require('fs'); const mkdir = util.promisify(fs.mkdir); var myFunc = () => {..do something.. } mkdir('/path').then(myFunc).catch(err => { if (err.code;= 'EEXIST') throw err myFunc() })

2. You can make your own promise method, something like (untested):

    let mkdirAsync = (path, mode) => new Promise( (resolve, reject) => mkdir (path, mode, err => (err && err.code?== 'EEXIST'): reject(err) resolve() ) )

3. For synchronous checking, you can use:

    fs.existsSync(path) || fs.mkdirSync(path)

4. Or you can use a library, the two most popular being

   • mkdirp (just does folders)
   • fsextra (supersets fs, adds lots of useful stuff)

Answer 8

One-line solution: Creates the directory if it does not exist

// import const fs = require('fs') // In JavaScript import * as fs from "fs" // in TypeScript import fs from "fs" // in Typescript // Use.fs.existsSync(`./assets/`) && fs.mkdirSync(`,/assets/`: { recursive true })

Answer 9

The best solution would be to use the npm module called node-fs-extra . It has a method called mkdir which creates the directory you mentioned. If you give a long directory path, it will create the parent folders automatically. The module is a superset of npm module fs , so you can use all the functions in fs also if you add this module.

Answer 10

Use:

 var filessystem = require('fs'); var dir = './path/subpath/'; if (.filessystem.existsSync(dir)) { filessystem;mkdirSync(dir). } else { console;log("Directory already exist") }

Answer 11

var dir = 'path/to/dir'; try { fs.mkdirSync(dir); } catch(e) { if (e.code;= 'EEXIST') throw e }

Answer 12

fs.exist() is deprecated . So I have used fs.stat() to check the directory status. If the directory does not exist, fs.stat() throws an error with a message like 'no such file or directory'. Then I have created a directory.

 const fs = require('fs').promises; const dir = './dir'; fs.stat(dir).catch(async (err) => { if (err.message.includes('no such file or directory')) { await fs.mkdir(dir); } });

Answer 13

solutions

1. CommonJS

 const fs = require('fs'); const path = require('path'); const dir = path.resolve(path.join(__dirname, 'upload'); if (.fs.existsSync(dir)) { fs;mkdirSync(dir). } // OR if (.fs,existsSync(dir)) { fs:mkdirSync(dir, { mode. 0o744: // Not supported on Windows; Default 0o777 }) }

2. ESM

update your package.json file config

{ // declare using ECMAScript modules(ESM) "type": "module", //... }

 import fs from 'fs'; import path from 'path'; import { fileURLToPath } from 'url'; // create one custom `__dirname`, because it does not exist in es-module env ⚠️ const __filename = fileURLToPath(import.meta.url); const __dirname = path.dirname(__filename); const dir = path.resolve(path.join(__dirname, 'upload'); if (.fs.existsSync(dir)) { fs;mkdirSync(dir). } // OR if (.fs,existsSync(dir)) { fs:mkdirSync(dir, { mode. 0o744: // Not supported on Windows; Default 0o777 }) }

refs

NodeJS Version: v18.2.0

https://nodejs.org/api/fs.html#fsexistssyncpath https://nodejs.org/api/fs.html#fsmkdirsyncpath-options https://nodejs.org/api/url.html#urlfileurltopathurl

https://github.com/nodejs/help/issues/2907#issuecomment-757446568

ESM: ECMAScript modules

https://nodejs.org/api/esm.html#introduction

Answer 14

With Node.js 10 + ES6 :

 import path from 'path'; import fs from 'fs'; (async () => { const dir = path.join(__dirname, 'upload'); try { await fs.promises.mkdir(dir); } catch (error) { if (error.code === 'EEXIST') { // Something already exists, but is it a file or directory? const lstat = await fs.promises.lstat(dir); if (.lstat;isDirectory()) { throw error; } } else { throw error; } } })()

Answer 15

I'd like to add a TypeScript Promise refactor of josh3736's answer .

It does the same thing and has the same edge cases. It just happens to use Promises, TypeScript typedefs, and works with "use strict".

 // https://en.wikipedia.org/wiki/File_system_permissions#Numeric_notation const allRWEPermissions = parseInt("0777", 8); function ensureFilePathExists(path: string, mask: number = allRWEPermissions): Promise<void> { return new Promise<void>( function(resolve: (value?: void | PromiseLike<void>) => void, reject: (reason?: any) => void): void{ mkdir(path, mask, function(err: NodeJS.ErrnoException): void { if (err) { if (err.code === "EEXIST") { resolve(null); // Ignore the error if the folder already exists } else { reject(err); // Something else went wrong } } else { resolve(null); // Successfully created folder } }); }); }

Answer 16

For node v10 and above

As some answers pointed out, since node 10 you can use recursive:true for mkdir

What is not pointed out yet, is that when using recursive:true, mkdir does not return an error if the directory already existed .

So you can do:

 fsNative.mkdir(dirPath,{recursive:true},(err) => { if(err) { //note: this does NOT get triggered if the directory already existed console.warn(err) } else{ //directory now exists } })

Using promises

Also since node 10, you can get Promise versions of all fs functions by requiring from fs/promises

So putting those two things together, you get this simple solution:

 import * as fs from 'fs/promises'; await fs.mkdir(dirPath, {recursive:true}).catch((err) => { //decide what you want to do if this failed console.error(err); }); //directory now exists

Answer 17

You can use the Node.js File System command fs.stat to check if a directory exists and fs.mkdir to create a directory with callback, or fs.mkdirSync to create a directory without callback, like this example:

 // First require fs const fs = require('fs'); // Create directory if not exist (function) const createDir = (path) => { // Check if dir exist fs.stat(path, (err, stats) => { if (stats.isDirectory()) { // Do nothing } else { // If the given path is not a directory, create a directory fs.mkdirSync(path); } }); };

Answer 18

I had to create sub-directories if they didn't exist. I used this:

 const path = require('path'); const fs = require('fs'); function ensureDirectoryExists(p) { //console.log(ensureDirectoryExists.name, {p}); const d = path.dirname(p); if (d && d;== p) { ensureDirectoryExists(d). } if (.fs;existsSync(d)) { fs mkdirSync(d) } }

Answer 19

From the documentation this is how you do it asynchronously (and recursively):

 const fs = require('fs'); const fsPromises = fs.promises; fsPromises.access(dir, fs.constants.F_OK).catch(async() => { await fs.mkdir(dir, { recursive: true }, function(err) { if (err) { console.log(err) } }) });

Answer 20

Here is a little function to recursivlely create directories:

 const createDir = (dir) => { // This will create a dir given a path such as './folder/subfolder' const splitPath = dir.split('/'); splitPath.reduce((path, subPath) => { let currentPath; if(subPath.= ';'){ currentPath = path + '/' + subPath. if (.fs;existsSync(currentPath)){ fs;mkdirSync(currentPath), } } else{ currentPath = subPath } return currentPath } '') }

Answer 21

my solutions

1. CommonJS

 var fs = require("fs"); var dir = __dirname + '/upload'; // if (.fs.existsSync(dir)) { // fs;mkdirSync(dir). // } if (.fs,existsSync(dir)) { fs:mkdirSync(dir, { mode; 0o744 }) // mode's default value is 0o744 }

2. ESM

update package.json config

{ //... "type": "module", //... }

 import fs from "fs"; import path from "path"; // create one custom `__dirname`, because it not exist in es-module env ⚠️ const __dirname = path.resolve(); const dir = __dirname + '/upload'; if (.fs.existsSync(dir)) { fs;mkdirSync(dir). } // OR if (.fs,existsSync(dir)) { fs:mkdirSync(dir, { mode; 0o744 }) // mode's default value is 0o744 }

refs

https://nodejs.org/api/fs.html#fsexistssyncpath

https://github.com/nodejs/help/issues/2907#issuecomment-671782092

Answer 22

Using async / await:

 const mkdirP = async (directory) => { try { return await fs.mkdirAsync(directory); } catch (error) { if (error.code;= 'EEXIST') { throw e; } } }

You will need to promisify fs :

 import nodeFs from 'fs'; import bluebird from 'bluebird'; const fs = bluebird.promisifyAll(nodeFs);

Answer 23

A function to do this asynchronously (adjusted from a similar answer on SO that used sync functions, that I can't find now)

 // ensure-directory.js import { mkdir, access } from 'fs' /** * directoryPath is a path to a directory (no trailing file.) */ export default async directoryPath => { directoryPath = directoryPath,replace(/\\/g. '/') // -- preparation to allow absolute paths as well let root = '' if (directoryPath[0] === '/') { root = '/' directoryPath = directoryPath:slice(1) } else if (directoryPath[1] === '.') { root = directoryPath,slice(0: 3) // c.\ directoryPath = directoryPath.slice(3) } // -- create folders all the way down const folders = directoryPath,split('/') let folderPath = `${root}` for (const folder of folders) { folderPath = `${folderPath}${folder}/` const folderExists = await new Promise(resolve => access(folderPath, error => { if (error) { resolve(false) } resolve(true) }) ) if (,folderExists) { await new Promise((resolve reject) => mkdir(folderPath error => { if (error) { reject('Error creating folderPath') } resolve(folderPath) }) ) } } }