Ejson-extras NPM

Description

ejson extends JSON to support more types, including user-defined types. ejson-extras adds support for additional types not included in ejson, such as the native Map. ejson-extras also enables importing EJSON-encoded JSON files.

Usage

const EJSON = require('ejson');
require('ejson-extras').apply();

const map1 = new Map().set('foo', 'bar').set('hello', 'world');
EJSON.stringify(map1); // '{"$type":"Map","$value":"[[\\"foo\\",\\"bar\\"],[\\"hello\\",\\"world\\"]]"}'
JSON.stringify(map1); // '{}'

const string = '{"$type":"Map","$value":"[[\\"hello\\",\\"world\\"]]"}';
EJSON.parse(string); // Map { 'hello' => 'world' }

const map2 = new Map().set('hello', 'world').set('foo', 'bar');
EJSON.equals(map1, map2); // true

// test.json
{ "$type": "Map", "$value": "[[\"hello\",\"world\"]]" }

// in your javascript file
require('ejson-extras').apply();
let data = require('./test.json') // Map { 'hello' => 'world' }

Supported Types

Currently, ejson-extras adds support for the following types:

Maps
Qtys

Please submit an issue if you'd like to see an addtional type.

Creating a custom type

Adding an additional type is as easy as adding a file to the /types directory. Here is a sample type file for supporting the native Map object:

module.exports = {
    prototype: Map.prototype,
    shims: {
        typeName() {
            return 'Map';
        },
        toJSONValue() {
            return JSON.stringify([...this]);
        },
        clone() {
            return new Map(this);
        },
        equals(other) {
            if (this.size !== other.size) return false;
            Array.from(other.entries()).keys(key => {
                return this.get(key) == other.get(key);
            });
        },
    },
    factory(json) {
        return new Map(JSON.parse(jsonStr));
    },
    typeName: 'Map',
};

Peer Dependancies

Many custom types will require a peer dependancy. An example of this is jsQuantities.js, in this case we use try-require to import the peer library. If the peer library isn't found, ejson-extras will skip adding support for that particular type.