docs/guide/javascript/index.md

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Apache Fory JavaScript lets you serialize JavaScript and TypeScript objects to bytes and deserialize them back, including across services written in Java, Python, C++, Go, Rust, C#, Swift, Dart, Scala, Kotlin, and other Fory-supported languages.

Why Fory JavaScript?

Xlang: serialize in JavaScript/TypeScript, deserialize in any supported Fory library without writing glue code
Fast: serializer code is generated and cached the first time you register a schema, not on every call
Reference-aware: shared references and circular object graphs are supported when enabled
Explicit schemas: field types, nullability, and polymorphism are declared once with Type.* builders or TypeScript decorators
Safe defaults: configurable depth checks reject unexpectedly deep payloads
Modern types: bigint, typed arrays, Map, Set, Date, float16, and bfloat16 are supported

Installation

Install the JavaScript packages from npm:

npm install @apache-fory/core

Optional Node.js string fast-path support is available through @apache-fory/hps:

npm install @apache-fory/core @apache-fory/hps

@apache-fory/hps depends on Node.js 20+ and is optional. If it is unavailable, Fory still works correctly; omit hps from the configuration.

Quick Start

import Fory, { Type } from "@apache-fory/core";

const userType = Type.struct(
  { typeName: "example.user" },
  {
    id: Type.int64(),
    name: Type.string(),
    age: Type.int32(),
  },
);

const fory = new Fory();
const { serialize, deserialize } = fory.register(userType);

const bytes = serialize({
  id: 1n,
  name: "Alice",
  age: 30,
});

const user = deserialize(bytes);
console.log(user);
// { id: 1n, name: 'Alice', age: 30 }

Generated Code from Fory IDL

You can also define schemas in Fory IDL and generate TypeScript model files:

package example;

message Person {
  string name = 1;
  int32 age = 2;
}

Generate JavaScript/TypeScript code:

foryc person.fdl --javascript_out=./generated

The generated model file exports TypeScript interfaces, enums, unions, a registration helper, and root serialization helpers:

import {
  Person,
  deserializePerson,
  registerPersonTypes,
  serializePerson,
} from "./generated/person";

const bytes = serializePerson({ name: "Alice", age: 30 });
const person: Person = deserializePerson(bytes);

When you manage your own Fory instance, register the generated schema module before serializing values with that instance:

import Fory from "@apache-fory/core";
import { registerPersonTypes } from "./generated/person";

const fory = new Fory();
const { person } = registerPersonTypes(fory);

const bytes = person.serialize({ name: "Alice", age: 30 });
const copy = person.deserialize(bytes);

How it works

Fory is schema-driven. You describe the shape of your data once with Type.* builders (or TypeScript decorators), then call fory.register(schema). This returns a { serialize, deserialize } pair that is fast to call repeatedly.

// 1. Define the schema
const personType = Type.struct("example.person", {
  name: Type.string(),
  email: Type.string().setNullable(true),
});

// 2. Register once
const fory = new Fory();
const { serialize, deserialize } = fory.register(personType);

// 3. Use as many times as needed
const bytes = serialize({ name: "Alice", email: null });
const person = deserialize(bytes);

Create one Fory instance per application and reuse it — creating a new one for every request wastes the work of schema registration.

Configuration

Fory JavaScript is xlang-only. new Fory() uses compatible schema evolution by default. Configure reference tracking, maximum read depth, and optional Node.js string acceleration through constructor options; see Configuration.

Documentation

Topic	Description
Basic Serialization	Core APIs and everyday usage
Configuration	Fory options, compatible mode, limits, and HPS
Type Registration	Numeric IDs, names, decorators, and schema registration
Schema Metadata	Type builders, field options, and decorators
Supported Types	Primitive, collection, time, enum, and struct mappings
References	Shared references and circular object graphs
Schema Evolution	Compatible mode and evolving structs
Xlang Serialization	Interop guidance and mapping rules
Fory IDL Compiler	Generate TypeScript models from `.fdl` schemas
gRPC Support	Node.js gRPC and browser gRPC-Web generated clients
Troubleshooting	Common issues, limits, and debugging tips