flatted

flatted

^{Social Media Photo by Matt Seymour on Unsplash}

A super light (0.5K) and fast circular JSON parser, directly from the creator of CircularJSON.

Available also for PHP.

Available also for Python.

Available also for Go.

ℹ️ JSON only values

If you need anything more complex than values JSON understands, there is a standard approach to recursion and more data-types than what JSON allows, and it's part of the Structured Clone polyfill.

npm i flatted

Usable via CDN or as regular module.

// ESM
import {parse, stringify, toJSON, fromJSON} from 'flatted';

// CJS
const {parse, stringify, toJSON, fromJSON} = require('flatted');

const a = [{}];
a[0].a = a;
a.push(a);

stringify(a); // [["1","0"],{"a":"0"}]

toJSON and fromJSON

If you'd like to implicitly survive JSON serialization, these two helpers helps:

import {toJSON, fromJSON} from 'flatted';

class RecursiveMap extends Map {
  static fromJSON(any) {
    return new this(fromJSON(any));
  }
  toJSON() {
    return toJSON([...this.entries()]);
  }
}

const recursive = new RecursiveMap;
const same = {};
same.same = same;
recursive.set('same', same);

const asString = JSON.stringify(recursive);
const asMap = RecursiveMap.fromJSON(JSON.parse(asString));
asMap.get('same') === asMap.get('same').same;
// true

Flatted VS JSON

As it is for every other specialized format capable of serializing and deserializing circular data, you should never JSON.parse(Flatted.stringify(data)), and you should never Flatted.parse(JSON.stringify(data)).

The only way this could work is to Flatted.parse(Flatted.stringify(data)), as it is also for CircularJSON or any other, otherwise there's no granted data integrity.

Also please note this project serializes and deserializes only data compatible with JSON, so that sockets, or anything else with internal classes different from those allowed by JSON standard, won't be serialized and unserialized as expected.

New in V1: Exact same JSON API

• Added a reviver parameter to .parse(string, reviver) and revive your own objects.
• Added a replacer and a space parameter to .stringify(object, replacer, space) for feature parity with JSON signature.

Compatibility

All ECMAScript engines compatible with Map, Set, Object.keys, and Array.prototype.reduce will work, even if polyfilled.

How does it work ?

While stringifying, all Objects, including Arrays, and strings, are flattened out and replaced as unique index. *

Once parsed, all indexes will be replaced through the flattened collection.

^{_{* represented as string to avoid conflicts with numbers}}

// logic example
var a = [{one: 1}, {two: '2'}];
a[0].a = a;
// a is the main object, will be at index '0'
// {one: 1} is the second object, index '1'
// {two: '2'} the third, in '2', and it has a string
// which will be found at index '3'

Flatted.stringify(a);
// [["1","2"],{"one":1,"a":"0"},{"two":"3"},"2"]
// a[one,two]    {one: 1, a}    {two: '2'}  '2'

Similar packages

Other packages similar to flatted

circular-json

CircularJSON is a JSON-like format that can encode circular structures and other complex data types. It is similar to flatted but was superseded by flatted due to its ability to handle more data types and its smaller footprint.

json-stringify-safe

json-stringify-safe is a package that can stringify objects with circular references without throwing. It works by replacing circular references with a string '[Circular]'. It is similar to flatted but does not allow for reconstruction of the original object with circular references.