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watchBlockNumber ​

Action that watches for block number changes.

Import ​

ts
import { watchBlockNumber } from '@wagmi/core'
import { watchBlockNumber } from '@wagmi/core'

Usage ​

ts
import { watchBlockNumber } from '@wagmi/core'
import { config } from './config'

const unwatch = watchBlockNumber(config, {
  onBlockNumber(blockNumber) {
    console.log('Block number changed!', blockNumber)
  },
})
unwatch()
import { watchBlockNumber } from '@wagmi/core'
import { config } from './config'

const unwatch = watchBlockNumber(config, {
  onBlockNumber(blockNumber) {
    console.log('Block number changed!', blockNumber)
  },
})
unwatch()
ts
import { http, createConfig } from '@wagmi/core'
import { mainnet, sepolia } from '@wagmi/core/chains'

export const config = createConfig({
  chains: [mainnet, sepolia],
  transports: {
    [mainnet.id]: http(),
    [sepolia.id]: http(),
  },
})
import { http, createConfig } from '@wagmi/core'
import { mainnet, sepolia } from '@wagmi/core/chains'

export const config = createConfig({
  chains: [mainnet, sepolia],
  transports: {
    [mainnet.id]: http(),
    [sepolia.id]: http(),
  },
})

Parameters ​

ts
import { type WatchBlockNumberParameters } from '@wagmi/core'
import { type WatchBlockNumberParameters } from '@wagmi/core'

chainId ​

config['chains'][number]['id'] | undefined

ID of chain to use when fetching data.

ts
import { watchBlockNumber } from '@wagmi/core'
import { mainnet } from '@wagmi/core/chains'
import { config } from './config'

const unwatch = watchBlockNumber(config, {
  chainId: mainnet.id, 
  onBlockNumber(blockNumber) {
    console.log('Block number changed!', blockNumber)
  },
})
unwatch()
import { watchBlockNumber } from '@wagmi/core'
import { mainnet } from '@wagmi/core/chains'
import { config } from './config'

const unwatch = watchBlockNumber(config, {
  chainId: mainnet.id, 
  onBlockNumber(blockNumber) {
    console.log('Block number changed!', blockNumber)
  },
})
unwatch()
ts
import { http, createConfig } from '@wagmi/core'
import { mainnet, sepolia } from '@wagmi/core/chains'

export const config = createConfig({
  chains: [mainnet, sepolia],
  transports: {
    [mainnet.id]: http(),
    [sepolia.id]: http(),
  },
})
import { http, createConfig } from '@wagmi/core'
import { mainnet, sepolia } from '@wagmi/core/chains'

export const config = createConfig({
  chains: [mainnet, sepolia],
  transports: {
    [mainnet.id]: http(),
    [sepolia.id]: http(),
  },
})

emitOnBegin ​

boolean | undefined

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

ts
import { watchBlockNumber } from '@wagmi/core'
import { config } from './config'

const unwatch = watchBlockNumber(config, {
  emitOnBegin: true, 
  onBlockNumber(blockNumber) {
    console.log('Block number changed!', blockNumber)
  },
})
unwatch()
import { watchBlockNumber } from '@wagmi/core'
import { config } from './config'

const unwatch = watchBlockNumber(config, {
  emitOnBegin: true, 
  onBlockNumber(blockNumber) {
    console.log('Block number changed!', blockNumber)
  },
})
unwatch()
ts
import { http, createConfig } from '@wagmi/core'
import { mainnet, sepolia } from '@wagmi/core/chains'

export const config = createConfig({
  chains: [mainnet, sepolia],
  transports: {
    [mainnet.id]: http(),
    [sepolia.id]: http(),
  },
})
import { http, createConfig } from '@wagmi/core'
import { mainnet, sepolia } from '@wagmi/core/chains'

export const config = createConfig({
  chains: [mainnet, sepolia],
  transports: {
    [mainnet.id]: http(),
    [sepolia.id]: http(),
  },
})

emitMissed ​

boolean | undefined

Whether or not to emit the missed block numbers to the callback.

ts
import { watchBlockNumber } from '@wagmi/core'
import { config } from './config'

const unwatch = watchBlockNumber(config, {
  emitMissed: true, 
  onBlockNumber(blockNumber) {
    console.log('Block number changed!', blockNumber)
  },
})
unwatch()
import { watchBlockNumber } from '@wagmi/core'
import { config } from './config'

const unwatch = watchBlockNumber(config, {
  emitMissed: true, 
  onBlockNumber(blockNumber) {
    console.log('Block number changed!', blockNumber)
  },
})
unwatch()
ts
import { http, createConfig } from '@wagmi/core'
import { mainnet, sepolia } from '@wagmi/core/chains'

export const config = createConfig({
  chains: [mainnet, sepolia],
  transports: {
    [mainnet.id]: http(),
    [sepolia.id]: http(),
  },
})
import { http, createConfig } from '@wagmi/core'
import { mainnet, sepolia } from '@wagmi/core/chains'

export const config = createConfig({
  chains: [mainnet, sepolia],
  transports: {
    [mainnet.id]: http(),
    [sepolia.id]: http(),
  },
})

onBlockNumber ​

(blockNumber: bigint, prevBlockNumber: bigint | undefined) => void

Callback for when block number changes.

ts
import { watchBlockNumber } from '@wagmi/core'
import { config } from './config'

const unwatch = watchBlockNumber(config, {
  onBlockNumber(blockNumber) { 
    console.log('Block number changed!', blockNumber) 
  }, 
})
unwatch()
import { watchBlockNumber } from '@wagmi/core'
import { config } from './config'

const unwatch = watchBlockNumber(config, {
  onBlockNumber(blockNumber) { 
    console.log('Block number changed!', blockNumber) 
  }, 
})
unwatch()
ts
import { http, createConfig } from '@wagmi/core'
import { mainnet, sepolia } from '@wagmi/core/chains'

export const config = createConfig({
  chains: [mainnet, sepolia],
  transports: {
    [mainnet.id]: http(),
    [sepolia.id]: http(),
  },
})
import { http, createConfig } from '@wagmi/core'
import { mainnet, sepolia } from '@wagmi/core/chains'

export const config = createConfig({
  chains: [mainnet, sepolia],
  transports: {
    [mainnet.id]: http(),
    [sepolia.id]: http(),
  },
})

onError ​

((error: Error) => void) | undefined

Error thrown from getting the block number.

ts
import { watchBlockNumber } from '@wagmi/core'
import { config } from './config'

const unwatch = watchBlockNumber(config, {
  onBlockNumber(blockNumber) { 
    console.log('Block number changed!', blockNumber) 
  }, 
  onError(error) { 
    console.error('Block number error', error) 
  }, 
})
unwatch()
import { watchBlockNumber } from '@wagmi/core'
import { config } from './config'

const unwatch = watchBlockNumber(config, {
  onBlockNumber(blockNumber) { 
    console.log('Block number changed!', blockNumber) 
  }, 
  onError(error) { 
    console.error('Block number error', error) 
  }, 
})
unwatch()
ts
import { http, createConfig } from '@wagmi/core'
import { mainnet, sepolia } from '@wagmi/core/chains'

export const config = createConfig({
  chains: [mainnet, sepolia],
  transports: {
    [mainnet.id]: http(),
    [sepolia.id]: http(),
  },
})
import { http, createConfig } from '@wagmi/core'
import { mainnet, sepolia } from '@wagmi/core/chains'

export const config = createConfig({
  chains: [mainnet, sepolia],
  transports: {
    [mainnet.id]: http(),
    [sepolia.id]: http(),
  },
})

poll ​

boolean | undefined

  • Whether or not to use a polling mechanism to check for new blocks instead of a WebSocket subscription.
  • Defaults to false for WebSocket Clients, and true for non-WebSocket Clients.
ts
import { watchBlockNumber } from '@wagmi/core'
import { config } from './config'

const unwatch = watchBlockNumber(config, {
  onBlockNumber(blockNumber) { 
    console.log('Block number changed!', blockNumber) 
  }, 
  poll: true, 
})
unwatch()
import { watchBlockNumber } from '@wagmi/core'
import { config } from './config'

const unwatch = watchBlockNumber(config, {
  onBlockNumber(blockNumber) { 
    console.log('Block number changed!', blockNumber) 
  }, 
  poll: true, 
})
unwatch()
ts
import { http, createConfig } from '@wagmi/core'
import { mainnet, sepolia } from '@wagmi/core/chains'

export const config = createConfig({
  chains: [mainnet, sepolia],
  transports: {
    [mainnet.id]: http(),
    [sepolia.id]: http(),
  },
})
import { http, createConfig } from '@wagmi/core'
import { mainnet, sepolia } from '@wagmi/core/chains'

export const config = createConfig({
  chains: [mainnet, sepolia],
  transports: {
    [mainnet.id]: http(),
    [sepolia.id]: http(),
  },
})

pollingInterval ​

number | undefined

ts
import { watchBlockNumber } from '@wagmi/core'
import { config } from './config'

const unwatch = watchBlockNumber(config, {
  onBlockNumber(blockNumber) { 
    console.log('Block number changed!', blockNumber) 
  }, 
  pollingInterval: 1_000, 
})
unwatch()
import { watchBlockNumber } from '@wagmi/core'
import { config } from './config'

const unwatch = watchBlockNumber(config, {
  onBlockNumber(blockNumber) { 
    console.log('Block number changed!', blockNumber) 
  }, 
  pollingInterval: 1_000, 
})
unwatch()
ts
import { http, createConfig } from '@wagmi/core'
import { mainnet, sepolia } from '@wagmi/core/chains'

export const config = createConfig({
  chains: [mainnet, sepolia],
  transports: {
    [mainnet.id]: http(),
    [sepolia.id]: http(),
  },
})
import { http, createConfig } from '@wagmi/core'
import { mainnet, sepolia } from '@wagmi/core/chains'

export const config = createConfig({
  chains: [mainnet, sepolia],
  transports: {
    [mainnet.id]: http(),
    [sepolia.id]: http(),
  },
})

syncConnectedChain ​

boolean | undefined

ts
import { watchBlockNumber } from '@wagmi/core'
import { config } from './config'

const unwatch = watchBlockNumber(config, {
  onBlockNumber(blockNumber) {
    console.log('Block number changed!', blockNumber)
  },
  syncConnectedChain: false, 
})
unwatch()
import { watchBlockNumber } from '@wagmi/core'
import { config } from './config'

const unwatch = watchBlockNumber(config, {
  onBlockNumber(blockNumber) {
    console.log('Block number changed!', blockNumber)
  },
  syncConnectedChain: false, 
})
unwatch()
ts
import { http, createConfig } from '@wagmi/core'
import { mainnet, sepolia } from '@wagmi/core/chains'

export const config = createConfig({
  chains: [mainnet, sepolia],
  transports: {
    [mainnet.id]: http(),
    [sepolia.id]: http(),
  },
})
import { http, createConfig } from '@wagmi/core'
import { mainnet, sepolia } from '@wagmi/core/chains'

export const config = createConfig({
  chains: [mainnet, sepolia],
  transports: {
    [mainnet.id]: http(),
    [sepolia.id]: http(),
  },
})

Return Type ​

ts
import { type WatchBlockNumberReturnType } from '@wagmi/core'
import { type WatchBlockNumberReturnType } from '@wagmi/core'

Function for cleaning up watcher.

Viem ​

Released under the MIT License.

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