javascript – Using Node.JS, how do I read a JSON file into (server) memory?

The Question :

673 people think this question is useful


I am doing some experimentation with Node.js and would like to read a JSON object, either from a text file or a .js file (which is better??) into memory so that I can access that object quickly from code. I realize that there are things like Mongo, Alfred, etc out there, but that is not what I need right now.


How do I read a JSON object out of a text or js file and into server memory using JavaScript/Node?

The Question Comments :

The Answer 1

1276 people think this answer is useful


var fs = require('fs');
var obj = JSON.parse(fs.readFileSync('file', 'utf8'));


var fs = require('fs');
var obj;
fs.readFile('file', 'utf8', function (err, data) {
  if (err) throw err;
  obj = JSON.parse(data);

The Answer 2

417 people think this answer is useful

The easiest way I have found to do this is to just use require and the path to your JSON file.

For example, suppose you have the following JSON file.


  "firstName": "Joe",
  "lastName": "Smith"

You can then easily load this in your node.js application using require

var config = require('./test.json');
console.log(config.firstName + ' ' + config.lastName);

The Answer 3

58 people think this answer is useful

Asynchronous is there for a reason! Throws stone at @mihai

Otherwise, here is the code he used with the asynchronous version:

// Declare variables
var fs = require('fs'),

// Read the file and send to the callback
fs.readFile('path/to/file', handleFile)

// Write the callback function
function handleFile(err, data) {
    if (err) throw err
    obj = JSON.parse(data)
    // You can now play with your datas

The Answer 4

45 people think this answer is useful

At least in Node v8.9.1, you can just do

var json_data = require('/path/to/local/file.json');

and access all the elements of the JSON object.

The Answer 5

17 people think this answer is useful

In Node 8 you can use the built-in util.promisify() to asynchronously read a file like this

const {promisify} = require('util')
const fs = require('fs')
const readFileAsync = promisify(fs.readFile)

readFileAsync(`${__dirname}/my.json`, {encoding: 'utf8'})
  .then(contents => {
    const obj = JSON.parse(contents)
  .catch(error => {
    throw error

The Answer 6

8 people think this answer is useful

using node-fs-extra (async await)

const readJsonFile = async () => {
  try {
    const myJsonObject = await fs.readJson('./my_json_file.json');
  } catch (err) {

readJsonFile() // prints your json object

The Answer 7

7 people think this answer is useful

Using fs-extra package is quite simple:


const fs = require('fs-extra')

const packageObj = fs.readJsonSync('./package.json')


const fs = require('fs-extra')

const packageObj = await fs.readJson('./package.json')

The Answer 8

3 people think this answer is useful
function parseIt(){
    return new Promise(function(res){
            var fs = require('fs');
            const dirPath = 'K:\\merge-xml-junit\\xml-results\\master.json';
                if(err) throw err;

async function test(){
    jsonData = await parseIt();
    var parsedJSON = JSON.parse(jsonData);
    var testSuite = parsedJSON['testsuites']['testsuite'];


The Answer 9

2 people think this answer is useful

var fs = require('fs');  

fs.readFile('/etc/passwd', (err, data) => {
  if (err) throw err;

// options
fs.readFile('/etc/passwd', 'utf8', callback);

You can find all usage of Node.js at the File System docs!
hope this help for you!

The Answer 10

0 people think this answer is useful

So many answers, and no one ever made a benchmark to compare sync vs async vs require. I described the difference in use cases of reading json in memory via require, readFileSync and readFile here.

The Answer 11

-1 people think this answer is useful

If you are looking for a complete solution for Async loading a JSON file from Relative Path with Error Handling

  // Global variables
  // Request path module for relative path
    const path = require('path')
  // Request File System Module
   var fs = require('fs');

// GET request for the /list_user page.
router.get('/listUsers', function (req, res) {
   console.log("Got a GET request for list of users");

     // Create a relative path URL
    let reqPath = path.join(__dirname, '../mock/users.json');

    //Read JSON from relative path of this file
    fs.readFile(reqPath , 'utf8', function (err, data) {
        //Handle Error
       if(!err) {
         //Handle Success
         // Parse Data to JSON OR
          var jsonObj = JSON.parse(data)
         //Send back as Response
          res.end( data );
        }else {
           //Handle Error
           res.end("Error: "+err )

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