Package Exports

@polkadot/rpc-core
@polkadot/rpc-core/index

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (@polkadot/rpc-core) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

@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 -

import Rpc from '@polkadot/rpc-core';
import WsProvider from '@polkadot/rpc-provider/ws';

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) => console.log(header))
  .catch((error) => console.error(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) => {
    console.log(`best #${header.blockNumber.toString()}`);
    console.log(`parentHash: ${header.parentHash.toString()}`);
    console.log(`stateRoot: ${header.stateRoot.toString()}`);
    console.log(`extrinsicsRoot: ${header.extrinsicsRoot.toString()}`);
    console.log(`digest: ${header.digest.toString()}`);
  })
  .catch((error) => {
    console.error('error:', error);
  });

Retrieving best header via subscription -

api.chain
  .subscribeNewHead((header) => {
    console.log(`best #${header.blockNumber}`);
  })
  .then((subscriptionId) => {
    console.log(`subscriptionId: ${subscriptionId}`);
    // id for the subscription, can unsubscribe via
    // api.chain.subscribeNewHead.unsubscribe(subscriptionId);
  })
  .catch((error) => {
    console.error('error subscribing:', error);
  });