@polkadot/api

Overview

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## Introduction `@polkadot/api` is a TypeScript library that wraps all methods exposed by Polkadot and Substrate network clients and defines every type the node exposes. It interacts with Polkadot- and Substrate-based blockchains via RPC calls. ## Core Mechanism The library's API is dynamically generated from the information provided in the Substrate runtime metadata. This means that when the underlying chain's runtime changes, the API automatically adapts to new interfaces and types without requiring manual maintenance of extensive hardcoded definitions. ## Key Capabilities - **Promise API**: Supports issuing queries and submitting transactions using standard Promise patterns. - **RxJS API**: Supports subscribing to on-chain state changes and handling asynchronous operations via RxJS reactive streams. - **Type Definitions**: Includes built-in definitions for all types exposed by the node, enabling type hints and checks in TypeScript projects. - **RPC Calls**: Communicates with chain nodes under the hood using the JSON-RPC protocol. ## Use Cases Ideal for developers who need to interact with blockchains in the Polkadot and Substrate ecosystems, such as building DApp frontends, writing off-chain services, or developing automation scripts. Full documentation and usage examples (including how to issue queries and submit transactions) are available on the official documentation portal. When upgrading versions, it is recommended to review the CHANGELOG.

Q&A

Which blockchains does this library support?AI-generated

It supports all Polkadot- and Substrate-based blockchain networks.

Is the API statically defined?AI-generated

No. The API is dynamically generated from the information provided in the Substrate runtime metadata.

Where can I find usage tutorials?AI-generated

You can find example guides on how to use the API to issue queries and submit transactions at the official documentation portal polkadot.js.org/docs/api/examples/promise/.

What should I watch out for when upgrading versions?AI-generated

It is recommended to review the CHANGELOG file in the repository when changing versions.