jsonj

jsonj (JSON serializer / deserializer)

Serialize and deserialize Javascript objects into JSON adding metadata if necessary for type information so objects are deserialized with the corresponding prototype. Typescript support.

Note: preliminary documentation

It will serialize and deserialize these values (which JSON.stringify and JSON.parse will not):

• NaN
• Infinity
• Date
• Buffer
• RegExp
• all builtin error constructs (Error, SyntaxError, TypeError, ReferenceError, RangeError, EvalError, URIError)

If any core javascript objects are missing, please submit an issue or pull request

Installation

npm install jsonj

Dependencies

none

API

jsonj.register(name, constructor, [ optionalFunctions ])

registers a constructor to serialize and deserialize

optionalFunctions

An object with either or both the below properties:

• serialize - Function to serialize an object. May return any value.
• deserialize - Function to reconstruct an object. Must return a constructed object

jsonj.serialize(value, [type])

Serializes value to a JSON representation. If the type is provided, no metadata will be included since it is assumed that the deserializing function knows what is the object is receiving.

jsonj.deserialize(json, [type])

Deserializes json to the provided type. If no type is provided, it will be obtained from metadata within the json object, if present.

 
var jsonj = require('jsonj');
 
function Person(name, age) {
    this.name = name;
    this.age = age;
}
 
Person.prototype.greet = function () {
    return 'hello, my name is ' + this.name + ' and I am ' + this.age + ' years old';
};
 
jsonj.register('Person', Person);
 
var me = new Person('Jayce', 22);
 
var json = jsonj.serialize(me); //no type information is given, so it is added as metadata
// {"__type":"Person","__data":{"name":"Jayce","age":22}}
 
var json2 = jsonj.serialize(me, Person); // resulting json can be simplified since we specify the type
// {"name":"Jayce","age":22}
 
var newMe = jsonj.deserialize(json);
 
newMe.greet();
// 'hello, my name is Jayce and I am 22 years old'
 
var newMe2 = jsonj.deserialize(json2,Person); // "cast" as Person when deserializing.
newMe2.greet();
// 'hello, my name is Jayce and I am 22 years old'
 
 

Custom serializers/deserializers

You can add custom serializers/derserializers by adding a serialize or deserialize function to your class. In JavaScript, as a function attached to the constructor. In TypeScript, these would be public static functions. You can also add serializers/deserializers by passing the functions to the register function.

serialize

If a serialize function was passed in the register call as an option, it is used. Otherwise, if the constructor has a serialize function, it is used to serialize the object instead. If neither are specified, then the object is serialized as key/value by default.

deserialize

If a deserialize function was passed in the registercall as an option, it is used. Otherwise, jsonj will try to call a deserialize static method of the class. If neither are specified, jsonj will copy the json data memberwise.

jsonj.unregister(name)

unregister a constructor from jsonj

serializeMetadata

You can add a dictionary with type metadata to a constructor to specify a white list of properties that you want serialized, along with type information that will allow for serializing without embedded metadata.

 
function Person(name, age) {
    this.name = name;
    this.age = age;
    this.birthDate = null;
    this.schools = [];
}
 
Person.prototype.sayHello = function () {
 
    console.log("Hello, I am " + this.name);
 
}
 
function School(name) {
    this.name = name;
}
 
Person.serializeMetadata = {
    name: "String",
    birthDate: "Date",
    schools: "School[]",
}
 

Credits

Some ideas, the builtins and some example text taken from jaycetde's jsoni parser, https://github.com/jaycetde/jsoni, though jsonj serializes to JSON rather than parsing JSON.