flatted

[snow flake]

Social Media Photo by Matt Seymour on Unsplash

Announcement 📣

There is a standard approach to recursion and more data-types than what
JSON allow, and it's part of this Structured Clone Module.

Beside acting as a polyfill, its @ungap/structured-clone/json export
provides both stringify and parse, and it's been tested for being faster
than flatted, but its produced output is also smaller than flatted.

The @ungap/structured-clone module is, in short, a drop in replacement
for flatted, but it's not compatible with flatted specialized syntax.

However, if recursion, as well as more data-types, are what you are
after, or interesting for your projects, consider switching to this new
module whenever you can 👍

------------------------------------------------------------------------

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

Now available also for PHP.

    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 from JSON

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'
