json-cycle

Utilities provide ability to encode/decode circular structures for converting to and from JSON.

Based on JSON-js

Install

In your project:

npm install json-cycle --save

Details

This package contains four functions, decycle, retrocycle, stringify and parse, which make it possible to encode cyclical structures and convert them to JSON, and then recover them. This is a capability that is not provided by ES5. JSONPath is used to represent the links. [http://GOESSNER.net/articles/JsonPath/]

Note: If you stringify javascript structure and then parse it back in some cases you can get not the same javascript structure. For instance, if it contains Date object you get String form of it.

Methods

• decycle
• retrocycle
• stringify
• parse

decycle(object)

Note: decycle function makes a deep copy of any provided structure while original decycle function from JSON-js does not make copy for Boolean, Date, Number, RegExp and String objects.

Makes a deep copy of an provided structure with resolving all circular references. The duplicate references which part of an cycle are replaced with an object of the form

{$ref: PATH}

where the PATH is a JSONPath string that locates the first occurrence.

Example:

1    jc = require('json-cycle');
2    var a = {};
3    a.self = a;
4    console.log(JSON.stringify(jc.decycle(a)));

Output:

1    {{"$ref":"$"}}

retrocycle(object)

returns provided object

Restores an object that was reduced by decycle function. Members whose values are objects of the form

{$ref: PATH}

are replaced with references to the value found by the PATH. This will restore cycles. The object will be mutated.

Note: The eval function is used to locate the values described by a PATH. The root object is kept in a $ variable. A regular expression is used to assure that the PATH is extremely well formed. The regexp contains nested

• quantifiers. That has been known to have extremely bad performance problems on some browsers for very long strings. A PATH is expected to be reasonably short. A PATH is allowed to belong to a very restricted subset of Goessner's JSONPath.

Example:

1    jc = require('json-cycle');
2    var s = '{{"$ref":"$"}}';
3    jc.retrocycle(JSON.parse(s));

Output:

1    produced object equals to 
2    var a = {};
3    a.self = a;

stringify(object)

It equals to JSON.stringify(decycle(object))

parse(object)

It equals to retrocycle(JSON.parse(object))

License

MIT © 2015-... Valery Barysok, Douglas Crockford