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Node.js - jsonfile
================
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Easily read/write JSON files in Node.js. _Note: this module cannot be used in the browser._
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[](https://www.npmjs.org/package/jsonfile)
[](http://travis-ci.org/jprichardson/node-jsonfile)
[](https://ci.appveyor.com/project/jprichardson/node-jsonfile/branch/master)
< a href = "https://github.com/feross/standard" > < img src = "https://cdn.rawgit.com/feross/standard/master/sticker.svg" alt = "Standard JavaScript" width = "100" > < / a >
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
---
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* [`readFile(filename, [options], callback)` ](#readfilefilename -options-callback)
* [`readFileSync(filename, [options])` ](#readfilesyncfilename -options)
* [`writeFile(filename, obj, [options], callback)` ](#writefilefilename -obj-options-callback)
* [`writeFileSync(filename, obj, [options])` ](#writefilesyncfilename -obj-options)
----
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### readFile(filename, [options], callback)
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`options` (`object` , default `undefined` ): Pass in any [`fs.readFile` ](https://nodejs.org/api/fs.html#fs_fs_readfile_path_options_callback ) options or set `reviver` for a [JSON reviver ](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/parse ).
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- `throws` (`boolean` , default: `true` ). If `JSON.parse` throws an error, pass this error to the callback.
If `false` , returns `null` for the object.
```js
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const jsonfile = require('jsonfile')
const file = '/tmp/data.json'
jsonfile.readFile(file, function (err, obj) {
if (err) console.error(err)
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console.dir(obj)
})
```
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You can also use this method with promises. The `readFile` method will return a promise if you do not pass a callback function.
```js
const jsonfile = require('jsonfile')
const file = '/tmp/data.json'
jsonfile.readFile(file)
.then(obj => console.dir(obj))
.catch(error => console.error(error))
```
----
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### readFileSync(filename, [options])
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`options` (`object` , default `undefined` ): Pass in any [`fs.readFileSync` ](https://nodejs.org/api/fs.html#fs_fs_readfilesync_path_options ) options or set `reviver` for a [JSON reviver ](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/parse ).
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- `throws` (`boolean` , default: `true` ). If an error is encountered reading or parsing the file, throw the error. If `false` , returns `null` for the object.
```js
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const jsonfile = require('jsonfile')
const file = '/tmp/data.json'
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console.dir(jsonfile.readFileSync(file))
```
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----
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### writeFile(filename, obj, [options], callback)
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`options` : Pass in any [`fs.writeFile` ](https://nodejs.org/api/fs.html#fs_fs_writefile_file_data_options_callback ) options or set `replacer` for a [JSON replacer ](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/stringify ). 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.
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```js
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const jsonfile = require('jsonfile')
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const file = '/tmp/data.json'
const obj = { name: 'JP' }
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jsonfile.writeFile(file, obj, function (err) {
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if (err) console.error(err)
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})
```
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Or use with promises as follows:
```js
const jsonfile = require('jsonfile')
const file = '/tmp/data.json'
const obj = { name: 'JP' }
jsonfile.writeFile(file, obj)
.then(res => {
console.log('Write complete')
})
.catch(error => console.error(error))
```
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**formatting with spaces:**
```js
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const jsonfile = require('jsonfile')
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const file = '/tmp/data.json'
const obj = { name: 'JP' }
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jsonfile.writeFile(file, obj, { spaces: 2 }, function (err) {
if (err) console.error(err)
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})
```
**overriding EOL:**
```js
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const jsonfile = require('jsonfile')
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const file = '/tmp/data.json'
const obj = { name: 'JP' }
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jsonfile.writeFile(file, obj, { spaces: 2, EOL: '\r\n' }, function (err) {
if (err) console.error(err)
})
```
**disabling the EOL at the end of file:**
```js
const jsonfile = require('jsonfile')
const file = '/tmp/data.json'
const obj = { name: 'JP' }
jsonfile.writeFile(file, obj, { spaces: 2, finalEOL: false }, function (err) {
if (err) console.log(err)
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})
```
**appending to an existing JSON file:**
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You can use `fs.writeFile` option `{ flag: 'a' }` to achieve this.
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```js
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const jsonfile = require('jsonfile')
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const file = '/tmp/mayAlreadyExistedData.json'
const obj = { name: 'JP' }
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jsonfile.writeFile(file, obj, { flag: 'a' }, function (err) {
if (err) console.error(err)
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})
```
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----
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### writeFileSync(filename, obj, [options])
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`options` : Pass in any [`fs.writeFileSync` ](https://nodejs.org/api/fs.html#fs_fs_writefilesync_file_data_options ) options or set `replacer` for a [JSON replacer ](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/stringify ). 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.
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```js
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const jsonfile = require('jsonfile')
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const file = '/tmp/data.json'
const obj = { name: 'JP' }
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jsonfile.writeFileSync(file, obj)
```
**formatting with spaces:**
```js
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const jsonfile = require('jsonfile')
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const file = '/tmp/data.json'
const obj = { name: 'JP' }
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jsonfile.writeFileSync(file, obj, { spaces: 2 })
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```
**overriding EOL:**
```js
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const jsonfile = require('jsonfile')
const file = '/tmp/data.json'
const obj = { name: 'JP' }
jsonfile.writeFileSync(file, obj, { spaces: 2, EOL: '\r\n' })
```
**disabling the EOL at the end of file:**
```js
const jsonfile = require('jsonfile')
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const file = '/tmp/data.json'
const obj = { name: 'JP' }
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jsonfile.writeFileSync(file, obj, { spaces: 2, finalEOL: false })
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```
**appending to an existing JSON file:**
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You can use `fs.writeFileSync` option `{ flag: 'a' }` to achieve this.
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```js
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const jsonfile = require('jsonfile')
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const file = '/tmp/mayAlreadyExistedData.json'
const obj = { name: 'JP' }
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jsonfile.writeFileSync(file, obj, { flag: 'a' })
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```
License
-------
(MIT License)
Copyright 2012-2016, JP Richardson < jprichardson @gmail .com >