docs/guide/javascript/index.md

title: JavaScript Serialization Guide sidebar_position: 0 id: index license: | Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to You under the Apache License, Version 2.0 (the “License”); you may not use this file except in compliance with the License. You may obtain a copy of the License at

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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, Go, Rust, Swift, and other Fory-supported languages.

Why Fory JavaScript?

Cross-language: serialize in JavaScript, deserialize in Java, Python, Go, and more 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, binary size, and collection size limits reject unexpectedly large or 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 }

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

import Fory from "@apache-fory/core";
import hps from "@apache-fory/hps";

const fory = new Fory({
  ref: true,
  compatible: true,
  maxDepth: 100,
  maxBinarySize: 64 * 1024 * 1024,
  maxCollectionSize: 1_000_000,
  hps,
});

Option	Default	Description
`ref`	`false`	Enable reference tracking for shared or circular object graphs
`compatible`	`false`	Allow field additions/removals without breaking existing messages
`maxDepth`	`50`	Maximum nesting depth. Must be `>= 2`. Increase for deeply nested structures
`maxBinarySize`	64 MiB	Maximum bytes accepted for any single binary field
`maxCollectionSize`	`1_000_000`	Maximum elements accepted in any list, set, or map
`useSliceString`	`false`	Optional string-reading optimization for Node.js. Leave at default unless benchmarked
`hps`	unset	Optional fast string helper from `@apache-fory/hps` (Node.js 20+)
`hooks.afterCodeGenerated`	unset	Callback to inspect the generated serializer code — useful for debugging

Documentation