Interface Summary
Interface	Description
SubmittableExtrinsic<ApplyResult>
SubmittableExtrinsic.StatusCb
Types
Types.ApiBaseInterface<ApplyResult>
Types.ApiInterfacePromise
Types.OnCallDefinition<ApplyResult>
Types.OnCallFunction
Types.Signer

Class Summary
Class	Description
ApiBase<ApplyResult>
ApiUtils
SubmittableExtrinsic.SubmittableExtrinsicImpl
SubmittableExtrinsic.SubmittableResult
Types.ApiOptions
Types.DecoratedRpc<ApplyResult>
Types.DecoratedRpcMethod<ApplyResult>
Types.DecoratedRpcSection<ApplyResult>
Types.Derive<ApplyResult>
Types.DeriveMethod<ApplyResult>
Types.DeriveSection<ApplyResult>
Types.QueryableModuleStorage<ApplyResult>
Types.QueryableStorage<ApplyResult>
Types.QueryableStorageFunction<ApplyResult>	export interface QueryableStorageFunctionBase<CodecResult, SubscriptionResult> extends StorageFunction { (arg?: CodecArg): CodecResult; at: (hash: Hash \| Uint8Array \| string, arg?: CodecArg) => CodecResult; hash: (arg?: CodecArg) => HashResult<CodecResult, SubscriptionResult>; key: (arg?: CodecArg) => string; size: (arg?: CodecArg) => U64Result<CodecResult, SubscriptionResult>; }
Types.SubmittableExtrinsicFunction<ApplyResult>
Types.SubmittableExtrinsics<ApplyResult>
Types.SubmittableModuleExtrinsics

Enum Summary
Enum Description

ApiBase.ApiType

Enum Summary
Enum	Description
ApiBase.ApiType

Package org.polkadot.api Description

@polkadot/rpc-core

This library provides a clean wrapper around all the methods exposed by a Polkadot network client.

Usage

Installation -

yarn add @polkadot/rpc-core

Initialisation -

const provider = new WsProvider("http://127.0.0.1:9944");
const api = new Rpc(provider);

Retrieving the block header object for a given block header hash (a 0x-prefixed hex string with length of 64) -

api.chain
 .getHeader("0x1234567890")
 .then((header) => System.out.println(header))
 .catch((error) => System.out.println(error));

Retrieving the best block number, parent hash, state root hash, extrinsics root hash, and digest (once-off) -

api.chain
 .getHead()
 .then((headerHash) => {
   return api.chain.getHeader(headerHash);
 })
 .then((header) => {
   System.out.print("best ");
   System.out.println(header.blockNumber);
   System.out.print("parentHash: ");
   System.out.println(header.parentHash.toString());
   System.out.print("stateRoot: ");
   System.out.println(header.stateRoot.toString());
   System.out.print("extrinsicsRoot: ");
   System.out.println(header.extrinsicsRoot.toString());
   System.out.print("digest: ");
   System.out.println(header.digest.toString());
 })
 .catch((error) => {
   System.out.println(error);
 });

Retrieving best header via subscription -

api.chain
 .subscribeNewHead((header) => {
   System.out.print("best ");
   System.out.println(header.blockNumber);
 })
 .then((subscriptionId) => {
   System.out.print("subscriptionId: ");
   System.out.println(subscriptionId);
   // id for the subscription, can unsubscribe via
   // api.chain.subscribeNewHead.unsubscribe(subscriptionId);
 })
 .catch((error) => {
   System.out.println(error);
 });