Ever needed to load, write and save a file in
node.js? Of course, I've heard of databases, but sometimes it's just way easier to write a small json file. 🔥
Creating a basic node.js app permalink
To read and write files in
node.js we need to include the file system package in our application.
First, we will create a basic application to test this. Open up your terminal and execute the following command.
Read more: Basic Node.js Express application
Note: Make sure you have
node.jsinstalled on your machine see nodejs website for the installation procedure.
mkdir fs-app && cd fs-app && npm init
This will create a directory called
fs-app, make the terminal change into this directory, and then execute the
npm init function.
npm init will create a default starting app for
Now we need to create our application index file. Open your favorite terminal and create an index.js file.
Installing the file system package in node.js permalink
To install the package, all we have to include in our index.js file is the following code:
const fs = require('fs');
All this does is tell our application we are planning to use the fs package. Now we can load json files, add changes and save them again.
Read a JSON file in Node JS permalink
To read a file, we will start by creating our demo file. Create a file called people.json and place the following content in it.
Now we add the following code to our index.js
let rawdata = fs.readFileSync('people.json');
let people = JSON.parse(rawdata);
If we now run
node index.js in our terminal we should see our json object logged out. 👏
Write json data to a file in node.js permalink
To write data back to the file, we will manipulate the contents of our json object, let's add another person and now save to the json file.
people.people because our index in the json file is called people, as well as the object we created. Then we tell the fs package to write to the people.json file the newly adjusted object.
Now, if we rerun
node index.js and open our people.json file, we should see two entries!
Congrats, you just read and write a json file in
You can find this project on GitHub