scanner

@open-web3/scanner

A monitoring library for Substrate based chain. It is more lightweight and generic, and has some unique features for low level data handling e.g. handle and decode batch calls.

Installation

Install it via

yarn add @open-web3/scanner
yarn add @polkadot/api

Other dependencies

If you are scanning a particular substrate chain that has custom types, you might need to install its types. In the example given below, please add this to dependencies.

"@acala-network/type-definitions": "0.4.0-beta.32"

Example

import Scanner from '@open-web3/scanner';
import { types, typesBundle } from '@acala-network/type-definitions';
import { WsProvider } from '@polkadot/rpc-provider';

const provider = new WsProvider('wss://node-6714447553777491968.jm.onfinality.io/ws');
await provider.isReady

const scanner = new Scanner({ wsProvider: provider, types, typesBundle });

scanner
  .subscribe({
    start: 0,
    end: 1000,
    confirmation: 4,
    concurrent: 10 // batch call
  })
  .subscribe((result) => {
    console.log(result.result.events);
  });

Scanner Method

scanner.subscribe(SubcribeOptions): Observable<SubscribeBlock | SubscribeBlockError>

Scans for events, transactions, and other data within the specified block height range.

Scanner Type

SubcribeOptions

Options passed to scanner

options.start ⇒ number

Height of the starting block of the scan. The default is 0.

options.end ⇒ number

Height of the ending block of the scan. If null, listen for the latest block.

options.confirmation ⇒ 'finalize' | number

If it is finalize, only finalized blocks are scanned

options.concurrent ⇒ number

The number of blocks that are resolved concurrently.

options.timeout ⇒ number

If a block resolution event exceeds timeout, an error is thrown

SubscribeBlock

subscribeBlock.blockNumber ⇒ number

Block height of resolved block.

subscribeBlock.result => Block

SubscribeBlockError

subscribeBlockError.blockNumber ⇒ number

Block height of resolved block.

subscribeBlockError.error ⇒ any

The error message

Block

block.raw ⇒ string;

Block of raw data

block.number ⇒ number;

Block height of resolved block.

block.hash ⇒ string;

Block hash of resolved block.

block.extrinsics ⇒ any;

All the transaction data for this block.

block.events ⇒ any[];

All the events data for this block.

block.author ⇒ string;

block.timestamp ⇒ number;