`jju` - a set of utilities to work with JSON / JSON5 documents
[](https://www.npmjs.org/package/jju)
[](https://travis-ci.org/rlidwka/jju)
[](https://www.npmjs.org/package/jju)
## Installation
```
yarn add jju
```
or
```
npm install jju
```
## Usage
This module provides following functions:
1. [jju.parse()](#jjuparse-function) parses json/json5 text and returns a javascript value it corresponds to
2. [jju.stringify()](#jjustringify-function) converts javascript value to an appropriate json/json5 text
3. [jju.tokenize()](#jjutokenize-function) parses json/json5 text and returns an array of tokens it consists of ([see demo](http://rlidwka.github.io/jju/tokenizer.html))
4. [jju.analyze()](#jjuanalyze-function) parses json/json5 text and tries to guess indentation, quoting style, etc.
5. [jju.update()](#jjuupdate-function) changes json/json5 text, preserving original formatting as much as possible ([see demo](http://rlidwka.github.io/jju/editor.html))
All functions are able to work with a standard JSON documents. `jju.parse()` and `jju.stringify()` are better in some cases, but slower than native `JSON.parse()` and `JSON.stringify()` versions. Detailed description see below.
### jju.parse() function
```javascript
/*
* Main syntax:
*
* `text` - text to parse, type: String
* `options` - parser options, type: Object
*/
jju.parse(text[, options])
// compatibility syntax
jju.parse(text[, reviver])
```
Options:
- reserved\_keys - what to do with reserved keys (String, default="ignore")
- "ignore" - ignore reserved keys
- "throw" - throw SyntaxError in case of reserved keys
- "replace" - replace reserved keys, this is the default JSON.parse behaviour, unsafe
Reserved keys are keys that exist in an empty object (`hasOwnProperty`, `__proto__`, etc.).
```javascript
// 'ignore' will cause reserved keys to be ignored:
parse('{hasOwnProperty: 1}', {reserved_keys: 'ignore'}) == {}
parse('{hasOwnProperty: 1, x: 2}', {reserved_keys: 'ignore'}).hasOwnProperty('x') == true
// 'throw' will cause SyntaxError in these cases:
parse('{hasOwnProperty: 1}', {reserved_keys: 'throw'}) == SyntaxError
// 'replace' will replace reserved keys with new ones:
parse('{hasOwnProperty: 1}', {reserved_keys: 'replace'}) == {hasOwnProperty: 1}
parse('{hasOwnProperty: 1, x: 2}', {reserved_keys: 'replace'}).hasOwnProperty('x') == TypeError
```
- null\_prototype - create object as Object.create(null) instead of '{}' (Boolean)
if `reserved_keys != 'replace'`, default is **false**
if `reserved_keys == 'replace'`, default is **true**
It is usually unsafe and not recommended to change this option to false in the last case.
- reviver - reviver function - Function
This function should follow JSON specification
- mode - operation mode, set it to 'json' if you want to throw on non-strict json files (String)
### jju.stringify() function
```javascript
/*
* Main syntax:
*
* `value` - value to serialize, type: *
* `options` - serializer options, type: Object
*/
jju.stringify(value[, options])
// compatibility syntax
jju.stringify(value[, replacer [, indent])
```
Options:
- ascii - output ascii only (Boolean, default=false)
If this option is enabled, output will not have any characters except of 0x20-0x7f.
- indent - indentation (String, Number or Boolean, default='\t')
This option follows JSON specification.
- quote - enquoting char (String, "'" or '"', default="'")
- quote\_keys - whether keys quoting in objects is required or not (String, default=false)
If you want `{"q": 1}` instead of `{q: 1}`, set it to true.
- sort\_keys - sort all keys while stringifying (Boolean or Function, default=false)
By default sort order will depend on implementation, with v8 it's insertion order. If set to `true`, all keys (but not arrays) will be sorted alphabetically. You can provide your own sorting function as well.
- replacer - replacer function or array (Function or Array)
This option follows JSON specification.
- no\_trailing\_comma = don't output trailing comma (Boolean, default=false)
If this option is set, arrays like this `[1,2,3,]` will never be generated. Otherwise they may be generated for pretty printing.
- mode - operation mode, set it to 'json' if you want correct json in the output (String)
Currently it's either 'json' or something else. If it is 'json', following options are implied:
- options.quote = '"'
- options.no\_trailing\_comma = true
- options.quote\_keys = true
- '\x' literals are not used
### jju.tokenize() function
```javascript
/*
* Main syntax:
*
* `text` - text to tokenize, type: String
* `options` - parser options, type: Object
*/
jju.tokenize(text[, options])
```
Options are the same as for the `jju.parse` function.
Return value is an array of tokens, where each token is an object:
- raw (String) - raw text of this token, if you join all raw's, you will get the original document
- type (String) - type of the token, can be `whitespace`, `comment`, `key`, `literal`, `separator` or `newline`
- stack (Array) - path to the current token in the syntax tree
- value - value of the token if token is a `key` or `literal`
You can check tokenizer for yourself using [this demo](http://rlidwka.github.io/jju/tokenizer.html).
### jju.analyze() function
```javascript
/*
* Main syntax:
*
* `text` - text to analyze, type: String
* `options` - parser options, type: Object
*/
jju.analyze(text[, options])
```
Options are the same as for the `jju.parse` function.
Return value is an object defining a programming style in which the document was written.
- indent (String) - preferred indentation
- newline (String) - preferred newline
- quote (String) - `"` or `'` depending on which quote is preferred
- quote\_keys (Boolean) - `true` if unquoted keys were used at least once
- has\_whitespace (Boolean) - `true` if input has a whitespace token
- has\_comments (Boolean) - `true` if input has a comment token
- has\_newlines (Boolean) - `true` if input has a newline token
- has\_trailing\_comma (Boolean) - `true` if input has at least one trailing comma
### jju.update() function
```javascript
/*
* Main syntax:
*
* `text` - original text, type: String
* `new_value` - new value you want to set
* `options` - parser or stringifier options, type: Object
*/
jju.update(text, new_value[, options])
```
If you want to update a JSON document, here is the general approach:
```javascript
// here is your original JSON document:
var input = '{"foo": "bar", "baz": 123}'
// you need to parse it first:
var json = jju.parse(input, {mode: 'json'})
// json is { foo: 'bar', baz: 123 }
// then you can change it as you like:
json.foo = 'quux'
json.hello = 'world'
// then you run an update function to change the original json:
var output = jju.update(input, json, {mode: 'json'})
// output is '{"foo": "quux", "baz": 123, "hello": "world"}'
```
Look at [this demo](http://rlidwka.github.io/jju/editor.html) to test various types of json.
## Advantages over existing JSON libraries
In a few cases it makes sense to use this module instead of built-in JSON methods.
Parser:
- better error reporting with source code and line numbers
In case of syntax error, JSON.parse does not return any good information to the user. This module does:
```
$ node -e 'require("jju").parse("[1,1,1,1,invalid]")'
SyntaxError: Unexpected token 'i' at 0:9
[1,1,1,1,invalid]
^
```
This module is about 5 times slower, so if user experience matters to you more than performance, use this module. If you're working with a lot of machine-generated data, use JSON.parse instead.
Stringifier:
- util.inspect-like pretty printing
This module behaves more smart when dealing with object and arrays, and does not always print newlines in them:
```
$ node -e 'console.log(require("./").stringify([[,,,],,,[,,,,]], {mode:"json"}))'
[
[null, null, null],
null,
null,
[null, null, null, null]
]
```
JSON.stringify will split this into 15 lines, and it's hard to read.
Yet again, this feature comes with a performance hit, so if user experience matters to you more than performance, use this module. If your JSON will be consumed by machines, use JSON.stringify instead.
As a rule of thumb, if you use "space" argument to indent your JSON, you'd better use this module instead.
![[ICO]](/icons/blank.gif){kind=icon}
![[PARENTDIR]](/icons/back.gif){kind=icon}
![[DIR]](/icons/folder.gif){kind=icon}
![[TXT]](/icons/text.gif){kind=icon}
![[ ]](/icons/unknown.gif){kind=icon}