watchBlockNumber #

Watches and returns incoming block numbers.

Import #

import { watchBlockNumber } from 'viem'

Usage #

Pass through your Public Client, along with a listener.

import { watchBlockNumber } from 'viem'
import { publicClient } from '.'
 
const unwatch = watchBlockNumber( 
  publicClient,
  blockNumber => console.log(blockNumber)
)
/**
 * > 69420n
 * > 69421n
 * > 69422n
 */

Listener #

(blockNumber: bigint) => void

The block number.

Returns #

UnwatchFn

A function that can be invoked to stop watching for new block numbers.

Configuration #

emitOnBegin (optional) #

• Type: boolean
• Default: false

Whether or not to emit the latest block number to the callback when the subscription opens.

const unwatch = watchBlockNumber(
  client,
  blockNumber => console.log(blockNumber),
  { emitOnBegin: true } 
)

pollingInterval (optional) #

• Type: number

Polling frequency (in ms). Defaults to Client's pollingInterval config.

const unwatch = watchBlockNumber(
  client,
  blockNumber => console.log(blockNumber),
  { pollingInterval: 12_000 } 
)

Example #