borsh

What is borsh?

The borsh npm package is a JavaScript implementation of the Binary Object Representation Serializer for Hashing (BORSH) serialization format. It is used to serialize and deserialize complex data structures in a compact binary format, which is particularly useful in blockchain and other performance-critical applications.

What are borsh's main functionalities?

Serialization

This feature allows you to serialize JavaScript objects into a binary format. The code sample demonstrates how to define a schema for a class and serialize an instance of that class.

const borsh = require('borsh');

class Greeting {
  constructor({ message }) {
    this.message = message;
  }
}

const schema = new Map([
  [Greeting, { kind: 'struct', fields: [['message', 'string']] }]
]);

const greeting = new Greeting({ message: 'Hello, world!' });
const serialized = borsh.serialize(schema, greeting);
console.log(serialized);

Deserialization

This feature allows you to deserialize binary data back into JavaScript objects. The code sample shows how to deserialize a binary array into an instance of a class using a predefined schema.

const borsh = require('borsh');

class Greeting {
  constructor({ message }) {
    this.message = message;
  }
}

const schema = new Map([
  [Greeting, { kind: 'struct', fields: [['message', 'string']] }]
]);

const serialized = new Uint8Array([10, 0, 0, 0, 72, 101, 108, 108, 111, 44, 32, 119, 111, 114, 108, 100, 33]);
const deserialized = borsh.deserialize(schema, Greeting, serialized);
console.log(deserialized);

Other packages similar to borsh

protobufjs

protobufjs is a JavaScript implementation of Protocol Buffers, a language-neutral, platform-neutral, extensible mechanism for serializing structured data. It is similar to borsh in that it provides efficient serialization and deserialization of complex data structures, but it uses a different format and is more widely adopted in various industries.

msgpack-lite

msgpack-lite is a JavaScript implementation of the MessagePack serialization format. Like borsh, it provides a compact binary format for serializing and deserializing data. However, MessagePack is a more general-purpose format and is used in a variety of applications beyond blockchain.

avsc

avsc is a JavaScript library for working with Avro, a data serialization system. Avro is similar to borsh in that it provides a compact binary format for data serialization, but it also includes features for schema evolution and is widely used in big data applications.

README

Borsh JS

Borsh JS is an implementation of the Borsh binary serialization format for JavaScript and TypeScript projects.

Borsh stands for Binary Object Representation Serializer for Hashing. It is meant to be used in security-critical projects as it prioritizes consistency, safety, speed, and comes with a strict specification.

Examples

(De)serializing a Value

import * as borsh from 'borsh';

const encodedU16 = borsh.serialize('u16', 2);
const decodedU16 = borsh.deserialize('u16', encodedU16);

const encodedStr = borsh.serialize('string', 'testing');
const decodedStr = borsh.deserialize('string', encodedStr);

(De)serializing an Object

import * as borsh from 'borsh';

const value = {x: 255, y: BigInt(20), z: '123', arr: [1, 2, 3]};
const schema = { struct: { x: 'u8', y: 'u64', 'z': 'string', 'arr': { array: { type: 'u8' }}}};

const encoded = borsh.serialize(schema, value);
const decoded = borsh.deserialize(schema, encoded);

API

The package exposes the following functions:

• serialize(schema: Schema, obj: any): Uint8Array - serializes an object obj according to the schema schema.
• deserialize(schema: Schema, buffer: Uint8Array, class?: Class): any - deserializes an object according to the schema schema from the buffer buffer. If the optional parameter class is present, the deserialized object will be an of class.

Schemas

Schemas are used to describe the structure of the data being serialized or deserialized. They are used to validate the data and to determine the order of the fields in the serialized data.

NOTE: You can find examples of valid in the test folder.

Basic Types

Basic types are described by a string. The following types are supported:

• u8, u16, u32, u64, u128 - unsigned integers of 8, 16, 32, 64, and 128 bits respectively.
• i8, i16, i32, i64, i128 - signed integers of 8, 16, 32, 64, and 128 bits respectively.
• f32, f64 - IEEE 754 floating point numbers of 32 and 64 bits respectively.
• bool - boolean value.
• string - UTF-8 string.

Arrays, Options, Maps, Sets, Enums, and Structs

More complex objects are described by a JSON object. The following types are supported:

• { array: { type: Schema, len?: number } } - an array of objects of the same type. The type of the array elements is described by the type field. If the field len is present, the array is fixed-size and the length of the array is len. Otherwise, the array is dynamic-sized and the length of the array is serialized before the elements.
• { option: Schema } - an optional object. The type of the object is described by the type field.
• { map: { key: Schema, value: Schema }} - a map. The type of the keys and values are described by the key and value fields respectively.
• { set: Schema } - a set. The type of the elements is described by the type field.
• { enum: [{ className1: { struct: {...} } }, { className2: { struct: {...} } }, ... ] } - an enum. The variants of the enum are described by the className1, className2, etc. fields. The variants are structs.
• { struct: { field1: Schema1, field2: Schema2, ... } } - a struct. The fields of the struct are described by the field1, field2, etc. fields.

Type Mappings

Javascript	Borsh
number	u8 u16 u32 i8 i16 i32
bigint	u64 u128 i64 i128
number	f32 f64
number	f32 f64
boolean	bool
string	UTF-8 string
type[]	fixed-size byte array
type[]	dynamic sized array
object	enum
Map	HashMap
Set	HashSet
null or type	Option

---

Contributing

Install dependencies:

yarn install

Continuously build with:

yarn dev

Run tests:

yarn test

Run linter

yarn lint

Publish

Prepare dist version by running:

yarn build

When publishing to npm use np.

License

This repository is distributed under the terms of both the MIT license and the Apache License (Version 2.0). See LICENSE-MIT and LICENSE-APACHE for details.