json-set-map

json-set-map

Set and Map extension that support JSON serialization and de-serialization

The original Set and Map object are not modified, so can still be used.

This library does not provides polyfills for Set and Map.

Install

yarn add json-set-map

The current version supports node v10.x+ and modern browsers.

Usage

• Typescript and es6

import { Set, Map } from 'json-set-map'

• Nodejs

var Set = require('json-set-map').Set;
var Map = require('json-set-map').Map;

The unmodified Set and Map class can still be used:

import { Set as jSet, Map as jMap } from 'json-set-map'
let originalMap = new Map()
let originalSet = new Set()
let serializableMap = new jMap()
let serializableSet = new jSet()

API

Method toJSON

Called automaticly by JSON.stringify

// Set
> originalSet.add(1).add(2)
< Set { 1, 2 }
> JSON.stringify(originalSet)
< '{}'
> serializableSet.add(1).add(2)
< SerializableSet { 1, 2 }
> JSON.stringify(serializableSet)
< '[1,2]'

// Map
> originalMap.set(1,2).set(3,4)
< Map { 1 => 2, 3 => 4 }
> JSON.stringify(originalMap)
< '{}'
> serializableMap.add(1).add(2)
< SerializableMap { 1 => 2, 3 => 4 }
> JSON.stringify(serializableMap)
< '[[1,2],[3,4]]'

Method fromJSON

Static method useful to load a Set or Map from the object returned by JSON.parse. A parser function can be used to load the objects of the array as shown in the example below.

> import { Set, Map } from 'json-set-map'

// Used without a parser it's the same as calling new Set
> Set.fromJSON(["2016-05-16T22:26:47.534Z","2016-05-16T22:26:47.533Z"])
< SerializableSet { '2016-05-16T22:26:47.534Z', '2016-05-16T22:26:47.533Z' } // Items are strings

// A parser function can be used to load the object.
> let parser=(d) => new Date(d)
> Set.fromJSON(["2016-05-16T22:26:47.534Z","2016-05-16T22:26:47.533Z"], { parser })
< SerializableSet { 2016-05-16T22:26:47.534Z, 2016-05-16T22:26:47.533Z } // Items are Dates

// Used without a parser it's the same as calling new Map 
> Map.fromJSON([['KeY','ValuE']])
< SerializableMap { 'KeY' => 'ValuE' }

// Separate parser function for the key and the value can be used.
> let keyParser = (item) => item.toUpperCase()
> let valueParser = (item) => item.toLowerCase()
> Map.fromJSON([['KeY','ValuE']], {keyParser, valueParser})
< SerializableMap { 'KEY' => 'value' }

Refer to the JSDoc documentation on the files for mode details.

Node

JSON does not support undefined and is replaced with null. This prevents the correct de-serialization of a Set with both undefined and null as element or of a Map with both element as key.

const str = JSON.stringify(new jSet().add(null).add(undefined)) // => '[null,null]'
jSet.fromJSON(JSON.parse(str))                                  // => SerializableSet { null }