fs.promises

Learn async file operations with fs.promises.

What is fs.promises?

In Node.js, file operations use the fs module. For asynchronous work the fs.promises sub-object is preferred; its methods return Promises and work with await.

import fs from 'fs/promises';
const data = await fs.readFile('notes.txt', 'utf8');

Here fs/promises provides Promise-based methods directly. The old fs module is callback-based; modern code prefers fs/promises. readFile, writeFile and appendFile are the most common methods.

import and await

You import the fs/promises module with import. In an ES modules environment you can use await directly at the top level of the module; otherwise you wrap it in an async function.

import fs from 'fs/promises';

async function run() {
  const data = await fs.readFile('notes.txt', 'utf8');
  console.log(data);
}
run();

Here the run async function awaits readFile and logs the content. The 'utf8' argument makes the result come back as a string; without it you get a Buffer.

Exercise Your turn: write with fs.promises

Import the module with import fs from 'fs/promises'. Define an async function run(). Inside, write to a file with await fs.writeFile('hello.txt', 'hello'). Log a message with console.log('written'). Call run().

Show example solution

import fs from 'fs/promises';

async function run() {
  await fs.writeFile('hello.txt', 'hello');
  console.log('written');
}
run();

Test yourself

Why is fs/promises preferred over the old fs module?
- Because it returns Promises and works with await
- Because it uses less memory
- Because it runs faster
- Because it is required
Show answer

Because it returns Promises and works with await — The Promise-based API enables a flat flow with await.

Fill in the blank: import fs

____ fs from 'fs/promises';

Show answer

import fs from 'fs/promises';

fs/promises parts

import

imports the module
fs/promises

Promise-based fs
await

waits for result

Next lesson: readFile

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