@polkadot/types

What is @polkadot/types?

@polkadot/types is a library for handling types and encoding/decoding of data for the Polkadot and Substrate ecosystem. It provides a comprehensive set of tools for working with the various types used in the Polkadot network, including creating, parsing, and validating data structures.

What are @polkadot/types's main functionalities?

Creating and Using Custom Types

This feature allows you to create and use custom types. In this example, a custom type 'u32' is created and initialized with the value 12345.

const { TypeRegistry } = require('@polkadot/types');
const registry = new TypeRegistry();
const MyCustomType = registry.createType('u32', 12345);
console.log(MyCustomType.toString()); // '12345'

Encoding and Decoding Data

This feature allows you to encode and decode data. In this example, a 'u32' type is encoded to a Uint8Array and then decoded back to its original value.

const { TypeRegistry } = require('@polkadot/types');
const registry = new TypeRegistry();
const encoded = registry.createType('u32', 12345).toU8a();
const decoded = registry.createType('u32', encoded);
console.log(decoded.toString()); // '12345'

Working with Complex Types

This feature allows you to work with complex types such as vectors and tuples. In this example, a vector of tuples containing 'u32' and 'bool' types is created and logged.

const { TypeRegistry } = require('@polkadot/types');
const registry = new TypeRegistry();
const ComplexType = registry.createType('Vec<(u32, bool)>', [[1, true], [2, false]]);
console.log(ComplexType.toString()); // '[[1,true],[2,false]]'

Other packages similar to @polkadot/types

ethers

The ethers.js library is a complete and compact library for interacting with the Ethereum blockchain and its ecosystem. It provides similar functionalities for encoding/decoding data and working with custom types, but it is tailored for the Ethereum network rather than Polkadot.

web3

web3.js is a collection of libraries that allow you to interact with a local or remote Ethereum node using HTTP, IPC, or WebSocket. It provides functionalities for encoding/decoding data and working with custom types, similar to @polkadot/types, but it is specific to the Ethereum blockchain.

bignumber.js

bignumber.js is a library for arbitrary-precision decimal and non-decimal arithmetic. While it does not provide the same breadth of functionality as @polkadot/types, it is often used in conjunction with blockchain libraries to handle large numbers and custom types.

README

@polkadot/types

Implementation of the types and their (de-)serialisation via SCALE codec. On the Rust side, the codec types and primitive types are implemented via the parity-codec.

Changelog

16.0.1 May 19, 2025

Breaking Changes:

• With the upgrade to Metadata v16, several fields have been removed or replaced. The following fields no longer exist in the updated metadata definitions:
  • type: This field has been completely removed in Metadata.
  • version: Previously part of ExtrinsicMetadata. Replaced by versions, which now holds an array Vec<u8> of supported extrinsic versions instead of a single value.
  • extraType: This field has been completely removed in ExtrinsicMetadata.
  • signedExtensions: Previously part of ExtrinsicMetadata. Replaced by transactionExtensions, which provides a more structured definition of extensions, and transactionExtensionsByVersion, mapping versions to active extensions.

Changes:

• Metadata v16 (#6130)
• Add dryRunApi v2 definition (#6144)
• Add type augmentation for AssetHub (#6148)
• Upgrade polkadot/common to 13.5.1 (#6150)