How to create a json file and read object data via node.js

1- Create a demo.js file
2- Inside the file, create a dependency to node.js' file system

var fs = require('fs')

Please note: variable fs can have any other variable name

3- Let's create a simple json file, call it data.json

Inside the file, let's add:

{"name":"Tim"}

4-  Save the file and go back to demo.js

5- Now that we have loaded the file system module, we are able to use the readFile() function to read the json file
6- In demo.js, add:

fs.readFile('./data.json', function(err,data){console.log(data)})

or

fs.readFile('./data.json', (err,data)=>{console.log(data)})

The second one is used more often since it is more compact.

The readFile() function allows you to use an anonymous function as a second parameter. In this anonymous function, you allow for error display and specified json file's data will be saved in a data variable. We then output the data in the console.

In this case, the output will be something like:

<Buffer 7b 0d 0a 20 20 22 6e 61 6d 65 22 3a 20 22 54 69 6d 22 0d 0a 7d 0d 0a>

This is because we need to specify the utf-8 format. It will look like this:

fs.readFile('./data.json', 'utf-8', (err,data)=>{console.log(data)})

Now the output will be:

{"name":"Tim"}

To read the exact value, we will need to treat the name property as an object by using:

var data = require('./data.json')

To see the output, use:

console.log(data.name)

An alternate way (using the previous example) is to use JSON.parse() to create the object:

fs.readFile('./data.json', (err,data)=>{var data = JSON.parse(data) console.log(data.name)})

Output for both examples will be:

Tim

Final code (using both methods):

var fs = require('fs')
var data = require('./data.json')

console.log(data.name)

fs.readFile('./data.json', 'utf-8', (err,data) => {
  var data = JSON.parse(data)
  console.log(data.name)
})