Node.js - jsonfile

Easily read/write JSON files in Node.js. Note: this module cannot be used in the browser.

Why?

Writing JSON.stringify() and then fs.writeFile() and JSON.parse() with fs.readFile() enclosed in try/catch blocks became annoying.

Installation

npm install --save jsonfile

API

• readFile(filename, [options], callback)
• readFileSync(filename, [options])
• writeFile(filename, obj, [options], callback)
• writeFileSync(filename, obj, [options])

---

readFile(filename, [options], callback)

options (object, default undefined): Pass in any fs.readFile options or set reviver for a JSON reviver.

• throws (boolean, default: true). If JSON.parse throws an error, pass this error to the callback. If false, returns null for the object.

1const jsonfile = require('jsonfile')
2const file = '/tmp/data.json'
3jsonfile.readFile(file, function (err, obj) {
4  if (err) console.error(err)
5  console.dir(obj)
6})

You can also use this method with promises. The readFile method will return a promise if you do not pass a callback function.

1const jsonfile = require('jsonfile')
2const file = '/tmp/data.json'
3jsonfile.readFile(file)
4  .then(obj => console.dir(obj))
5  .catch(error => console.error(error))

---

readFileSync(filename, [options])

options (object, default undefined): Pass in any fs.readFileSync options or set reviver for a JSON reviver.

• throws (boolean, default: true). If an error is encountered reading or parsing the file, throw the error. If false, returns null for the object.

1const jsonfile = require('jsonfile')
2const file = '/tmp/data.json'
3
4console.dir(jsonfile.readFileSync(file))

---

writeFile(filename, obj, [options], callback)

options: Pass in any fs.writeFile options or set replacer for a JSON replacer. Can also pass in spaces, or override EOL string or set finalEOL flag as false to not save the file with EOL at the end.

1const jsonfile = require('jsonfile')
2
3const file = '/tmp/data.json'
4const obj = { name: 'JP' }
5
6jsonfile.writeFile(file, obj, function (err) {
7  if (err) console.error(err)
8})

Or use with promises as follows:

1const jsonfile = require('jsonfile')
2
3const file = '/tmp/data.json'
4const obj = { name: 'JP' }
5
6jsonfile.writeFile(file, obj)
7  .then(res => {
8    console.log('Write complete')
9  })
10  .catch(error => console.error(error))

formatting with spaces:

1const jsonfile = require('jsonfile')
2
3const file = '/tmp/data.json'
4const obj = { name: 'JP' }
5
6jsonfile.writeFile(file, obj, { spaces: 2 }, function (err) {
7  if (err) console.error(err)
8})

overriding EOL:

1const jsonfile = require('jsonfile')
2
3const file = '/tmp/data.json'
4const obj = { name: 'JP' }
5
6jsonfile.writeFile(file, obj, { spaces: 2, EOL: '\r\n' }, function (err) {
7  if (err) console.error(err)
8})

disabling the EOL at the end of file:

1const jsonfile = require('jsonfile')
2
3const file = '/tmp/data.json'
4const obj = { name: 'JP' }
5
6jsonfile.writeFile(file, obj, { spaces: 2, finalEOL: false }, function (err) {
7  if (err) console.log(err)
8})

appending to an existing JSON file:

You can use fs.writeFile option { flag: 'a' } to achieve this.

1const jsonfile = require('jsonfile')
2
3const file = '/tmp/mayAlreadyExistedData.json'
4const obj = { name: 'JP' }
5
6jsonfile.writeFile(file, obj, { flag: 'a' }, function (err) {
7  if (err) console.error(err)
8})

---

writeFileSync(filename, obj, [options])

options: Pass in any fs.writeFileSync options or set replacer for a JSON replacer. Can also pass in spaces, or override EOL string or set finalEOL flag as false to not save the file with EOL at the end.

1const jsonfile = require('jsonfile')
2
3const file = '/tmp/data.json'
4const obj = { name: 'JP' }
5
6jsonfile.writeFileSync(file, obj)

formatting with spaces:

1const jsonfile = require('jsonfile')
2
3const file = '/tmp/data.json'
4const obj = { name: 'JP' }
5
6jsonfile.writeFileSync(file, obj, { spaces: 2 })

overriding EOL:

1const jsonfile = require('jsonfile')
2
3const file = '/tmp/data.json'
4const obj = { name: 'JP' }
5
6jsonfile.writeFileSync(file, obj, { spaces: 2, EOL: '\r\n' })

disabling the EOL at the end of file:

1const jsonfile = require('jsonfile')
2
3const file = '/tmp/data.json'
4const obj = { name: 'JP' }
5
6jsonfile.writeFileSync(file, obj, { spaces: 2, finalEOL: false })

appending to an existing JSON file:

You can use fs.writeFileSync option { flag: 'a' } to achieve this.

1const jsonfile = require('jsonfile')
2
3const file = '/tmp/mayAlreadyExistedData.json'
4const obj = { name: 'JP' }
5
6jsonfile.writeFileSync(file, obj, { flag: 'a' })

License

(MIT License)

Copyright 2012-2016, JP Richardson jprichardson@gmail.com