AI Workshop: learn to build apps with AI →
Working with Files: How to write a JSON object to file in Node.js

Join the AI Workshop and learn to build real-world apps with AI. A hands-on, practical program to level up your skills.


Sometimes the best way to store some data in a Node.js application is to save it to the filesystem.

If you have an object that can be serialized to JSON, you can use the JSON.stringify() method and the fs method fs.writeFileSync() which synchronously writes a piece of data to a file:

const fs = require('fs')

const storeData = (data, path) => {
  try {
    fs.writeFileSync(path, JSON.stringify(data))
  } catch (err) {
    console.error(err)
  }
}

To retrieve the data, you can use fs.readFileSync():

const loadData = (path) => {
  try {
    return fs.readFileSync(path, 'utf8')
  } catch (err) {
    console.error(err)
    return false
  }
}

The synchronous API makes it easy to return the data directly.

For asynchronous versions, use fs.writeFile and fs.readFile. See how to write files using Node.js and how to read files using Node.js for the async APIs.

Lessons in this unit:

0: Introduction
1: How to check if a file exists in Node.js
2: How to create an empty file in Node.js
3: How to get the names of all the files in a folder in Node
4: How to get the last updated date of a file using Node.js
5: How to remove a file with Node.js
6: ▶︎ How to write a JSON object to file in Node.js
7: How to empty a folder in Node.js
8: Working with file descriptors in Node
9: Node File Paths
10: Node file stats
11: Working with folders in Node
12: How to use the Node.js fs module with async/await
13: How to get the current folder in Node
14: How to get the file extension in Node.js from the MIME type
15: How to get the file extension in Node.js
16: How to list files in a folder in Node
17: How to mass rename files in Node.js
18: Node.js get all files in a folder recursively
19: Incrementing multiple folders numbers at once using Node.js
20: Save some text to a file in Node.js