docs/guide/javascript/index.md

---
title: JavaScript Serialization Guide
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  this work for additional information regarding copyright ownership.
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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:

```bash
npm install @apache-fory/core
```

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

```bash
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

```ts
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:

```protobuf
package example;

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

Generate JavaScript/TypeScript code:

```bash
foryc person.fdl --javascript_out=./generated
```

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

```ts
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:

```ts
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.

```ts
// 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](configuration.md).

## Documentation

| Topic                                         | Description                                             |
| --------------------------------------------- | ------------------------------------------------------- |
| [Basic Serialization](basic-serialization.md) | Core APIs and everyday usage                            |
| [Configuration](configuration.md)             | Fory options, compatible mode, limits, and HPS          |
| [Type Registration](type-registration.md)     | Numeric IDs, names, decorators, and schema registration |
| [Schema Metadata](schema-metadata.md)         | Type builders, field options, and decorators            |
| [Supported Types](supported-types.md)         | Primitive, collection, time, enum, and struct mappings  |
| [References](references.md)                   | Shared references and circular object graphs            |
| [Schema Evolution](schema-evolution.md)       | Compatible mode and evolving structs                    |
| [Xlang Serialization](xlang-serialization.md) | Interop guidance and mapping rules                      |
| [Fory IDL Compiler](../../compiler/index.md)  | Generate TypeScript models from `.fdl` schemas          |
| [gRPC Support](grpc-support.md)               | Node.js gRPC and browser gRPC-Web generated clients     |
| [Troubleshooting](troubleshooting.md)         | Common issues, limits, and debugging tips               |

## Related Resources

- [Xlang Serialization Specification](../../specification/xlang_serialization_spec.md)
- [Xlang Type Mapping](../../specification/xlang_type_mapping.md)