json-recursive

Yet-another-recursive-JSON.stringify()-implementation.

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Install

npm install --save @anyhowstep/json-recursive

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Test

npm run test-all

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Build

npm run build

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Basic Usage (stringify(), parse())

import * as json from "@anyhowstep/json-recursive";

const x : any = {};
const y : any = {};
x.y = y;
y.x = x;

//{"y":{"x":{"$recursive":[]}}}
const str = json.stringify(x);
//`obj` has same structure as `x`
const obj = json.parse(str);

import * as json from "@anyhowstep/json-recursive";

const arr : any[] = [];
arr.push(arr);

//[{"$recursive":[]}]
const str = json.stringify(arr);
//`obj` has same structure as `arr`
const obj = json.parse(str);

import * as json from "@anyhowstep/json-recursive";

const x : any = {};
x.y = {};
x.z = {};
x.y.z = x.z;
x.z.y = x.y;
x.x = x;

//{"y":{"z":{"y":{"$recursive":["y"]}}},"z":{"$recursive":["y","z"]},"x":{"$recursive":[]}}
const str = json.stringify(x);
//`obj` has same structure as `x`
const obj = json.parse(str);

import * as json from "@anyhowstep/json-recursive";

const x : any = {};
x.x = x;
x.date = new Date();

//{"x":{"$recursive":[]},"date":"2018-09-07T20:23:46.427Z"}
const str = json.stringify(x);
//`obj` has same structure as `x`
//But `obj.date` is of type `string`
//because JSON.stringify() does that.
const obj = json.parse(str);

stringify() may return undefined; particularly, JSON.stringify(undefined).

stringifyOrError() will return string or throw an Error.

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Caveats

As you can see, recursive objects have the structure,

{ $recursive : string[] }

Therefore, in general $recursive is a reserved field.

TODO: Maybe allow one to set the field to use for recursion?

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ReplacerDelegate

stringify() allows you to use a ReplacerDelegate.

export type ReplacerDelegate = (this : any, key : string, value : any) => any;

import * as json from "@anyhowstep/json-recursive";
//`json.includeError` is a replacer delegate
//that stringifies instances of `Error`.
//Normally, instances of `Error` get stringified to empty objects.

const x : any = {};
x.x = x;
x.error = new Error("This is a test message");

//{"x":{"$recursive":[]},"error":{"name":"Error","message":"This is a test message","stack":"Error: This is a test message\n    at Test.tape"}}
const str = json.stringify(x, json.includeError);
//`obj` has same structure as `x`
//But `obj.error` is not an instance of `Error`
const obj = json.parse(str);

import * as json from "@anyhowstep/json-recursive";
//`json.ignoreLeadingUnderscoreKey` is a replacer delegate
//that ignores keys beginning with underscores.

const x : any = {};
x._x = x;
x.y = {
    x : x,
    _x : x,
};

//{"y":{"x":{"$recursive":[]}}}
const str = json.stringify(x, json.ignoreLeadingUnderscoreKey);
//`obj` has same structure as `x`
//But `obj._x` does not exist
//and `obj.y._x` does not exist
const obj = json.parse(str);

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Chaining Replacers

ReplacerDelegates may be chained.

const str = json.stringifyOrError(x, json.chainReplacers(
    json.includeError,
    json.ignoreLeadingUnderscoreKey
));