Serializing an ES6 class object as JSON

Question

class MyClass {
  constructor() {
    this.foo = 3
  }
}

var myClass = new MyClass()

I'd like to serialize myClass object to json.

One easy way I can think of is, since every member is actually javascript object (array, etc..) I guess I can maintain a variable to hold the member variables.

this.prop.foo = this.foo and so on.

I expected to find a toJSON/fromJSON library for class objects since I used them with other languages such as swift/java, but couldn't find one for javascript.

Maybe class construct is too new, or what I'm asking can be somehow easily achieved without a library.

Answer 1

As with any other object you want to stringify in JS, you can use JSON.stringify:

JSON.stringify(yourObject); 

---

class MyClass {    constructor() {      this.foo = 3    }  }    var myClass = new MyClass()    console.log(JSON.stringify(myClass));

Also worth noting is that you can customize how stringify serializes your object by giving it a toJSON method. The value used to represent your object in the resulting JSON string will be the result of calling the toJSON method on that object.

Answer 2

I know this question is old but I've been clawing my eyes out until I wrote a compact real, "safe", solution.

Deserialization returns objects that still have working methods attached to them.

The only thing you need to do is register the classes you want to use in the constructor of the serializer.

---

class Serializer{
    constructor(types){this.types = types;}
    serialize(object) {
        let idx = this.types.findIndex((e)=> {return e.name == object.constructor.name});
        if (idx == -1) throw "type  '" + object.constructor.name + "' not initialized";
        return JSON.stringify([idx, Object.entries(object)]);
    }
    deserialize(jstring) {
        let array = JSON.parse(jstring);
        let object = new this.types[array[0]]();
        array[1].map(e=>{object[e[0]] = e[1];});
        return object;
    }
}

class MyClass {
    constructor(foo) {this.foo = foo;}
    getFoo(){return this.foo;}
}

var serializer = new Serializer([MyClass]);

console.log(serializer.serialize(new MyClass(42)));
//[0,[["foo",42]]]

console.log(serializer.deserialize('[0,[["foo",42]]]').getFoo());
//42

The above should be enough to get you going, but more details and minified version can be found here.