A lightweight JavaScript sdk to connect to the Blocknative backend Ethereum node infrastructure via a websocket connection for realtime transaction updates.
npm install bnc-sdk
import WebSocket from 'ws'
import BlocknativeSdk from 'bnc-sdk'
import Web3 from 'web3'
const web3 = new Web3('<ws://some.local-or-remote.node:8546>')
// create options object
const options = {
dappId: '<YOUR_API_KEY>',
networkId: 4,
ws: WebSocket
// un-comment if you would like to log all transaction events
// transactionHandlers: [event => console.log(event.transaction)]
}
// initialize and connect to the api
const blocknative = new BlocknativeSdk(options)
const txOptions = {
to: '0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D',
value: 1000000000000000
}
// initiate a transaction via web3.js
web3.eth.sendTransaction(txOptions).on('transactionHash', hash => {
// call with the transaction hash of the transaction that you would like to receive status updates for
const { emitter } = blocknative.transaction(hash)
// listen to some events
emitter.on('txPool', transaction => {
console.log(`Sending ${transaction.value} wei to ${transaction.to}`)
})
emitter.on('txConfirmed', transaction => {
console.log('Transaction is confirmed!')
})
// catch every other event that occurs and log it
emitter.on('all', transaction => {
console.log(`Transaction event: ${transaction.eventCode}`)
})
})import WebSocket from 'ws'
import BlocknativeSdk from 'bnc-sdk'
import Web3 from 'web3'
const web3 = new Web3('<ws://some.local-or-remote.node:8546>')
// create options object
const options = {
dappId: '<YOUR_API_KEY>',
networkId: 4,
ws: WebSocket
// un-comment if you would like to log all transaction events
// transactionHandlers: [event => console.log(event.transaction)]
}
// initialize and connect to the api
const blocknative = new BlocknativeSdk(options)
const address = '0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D'
const { emitter, details } = blocknative.account(address)
emitter.on('all', transaction => {
console.log(transaction)
})import BlocknativeSdk from 'bnc-sdk'
import Web3 from 'web3'
const web3 = new Web3(window.ethereum)
// create options object
const options = {
dappId: '<YOUR_API_KEY>',
networkId: 4
// un-comment if you would like to log all transaction events
// transactionHandlers: [event => console.log(event.transaction)]
}
// initialize and connect to the api
const blocknative = new BlocknativeSdk(options)
const txOptions = {
to: '0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D',
value: 1000000000000000
}
// initiate a transaction via web3.js
web3.eth.sendTransaction(txOptions).on('transactionHash', hash => {
// call with the transaction hash of the transaction that you would like to receive status updates for
const { emitter } = blocknative.transaction(hash)
// listen to some events
emitter.on('txPool', transaction => {
console.log(`Sending ${transaction.value} wei to ${transaction.to}`)
})
emitter.on('txConfirmed', transaction => {
console.log('Transaction is confirmed!')
})
// catch every other event that occurs and log it
emitter.on('all', transaction => {
console.log(`Transaction event: ${transaction.eventCode}`)
})
})Transaction Preview lets you preview the outputs of any custom transactions that you submit to it. By harnessing the power of our network of Ethereum nodes, with our existing decoding and transaction lifecycle knowledge, we hope to give users of Transaction Preview even greater comfort when interacting in the Web3 space. Previewing a transaction is particularly useful for: Wallets: Help users preview net-balance changes & identify malicious contract behavior or buggy smart contracts before interacting with them. DEXs & Swaps: Report accurate slippage, Accurate tokens received, and accurate failing calls Traders: Preview many iterations of the same trade and execute only the most profitable one Lending Protocols: Tell whether a Borrow / Repay / Claim transaction will go through Auctions: Tell whether your bid or listing will go through and its accuracy & effects NFTs: Tell whether your NFT mint, purchase, or transfer will go through & much more without spending a single wei in gas!
Transaction Preview is currently only supported for Ethereum: Main. Please stay tuned for its availability on other networks supported by Blocknative.
Usage rate limit for the Transaction Preview API is 100 requests per 60-second window. Transaction Preview consumes the same daily limits on your Blocknative plan as pending simulated transactions in Simulation Platform. You can view your current consumption on your Blocknative Account Page.
This example will mock a contract interaction between two wallets.
import BlocknativeSdk, { SimulationTransaction, MultiSimOutput } from 'bnc-sdk'
import { SimulationTransaction, MultiSimOutput } from 'bnc-sdk'
import { ethers } from 'ethers'
const addressFrom = '0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045'
const CONTRACT_ADDRESS = '0x7a250d5630b4cf539739df2c5dacb4c659f2488d'
const erc20_interface = [
'function approve(address _spender, uint256 _value) public returns (bool success)',
'function transferFrom(address sender, address recipient, uint256 amount) external returns (bool)',
'function balanceOf(address owner) view returns (uint256)'
]
const uniswapV2router_interface = [
'function swapExactTokensForETH(uint amountIn, uint amountOutMin, address[] calldata path, address to, uint deadline) external returns (uint[] memory amounts)'
]
const weth = '0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2'
const dai = '0x6B175474E89094C44Da98b954EedeAC495271d0F'
let swapTxData
let approveTxData
const createTransaction = async () => {
const swapContract = new ethers.Contract(
CONTRACT_ADDRESS,
uniswapV2router_interface
)
const erc20_contract = new ethers.Contract(weth, erc20_interface)
const oneEther = ethers.BigNumber.from('1591000000000000000000')
approveTxData = await erc20_contract.populateTransaction.approve(
CONTRACT_ADDRESS,
oneEther
)
const amountOutMin = 0
const amountOutMinHex = ethers.BigNumber.from(amountOutMin.toString())._hex
const path = [dai, weth]
const deadline = Math.floor(Date.now() / 1000) + 60 * 1 // 1 minutes from the current Unix time
const inputAmountHex = oneEther.toHexString()
swapTxData = await swapContract.populateTransaction.swapExactTokensForETH(
inputAmountHex,
amountOutMinHex,
path,
addressFrom,
deadline
)
}
await createTransaction()
const account_address = '0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045'
const uniswapV2Router = '0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D'
const stubTrans = [
{
from: account_address,
to: dai,
input: approveTxData.data,
gas: 1000000,
gasPrice: 48000000000,
value: 0
},
{
from: account_address,
to: uniswapV2Router,
input: swapTxData.data,
gas: 1000000,
gasPrice: 48000000000,
value: 0
}
]
// create options object
const options = {
dappId: '<YOUR_API_KEY>',
networkId: 1
}
// initialize and connect to the api
const blocknativeSDK = new BlocknativeSdk(options)
const singleSim: Promise<SimulationTransactionOutput> = blocknativeSDK.simulate(
'ethereum',
'main',
stubTrans[1]
)
const multiSim: Promise<MultiSimOutput> = blocknativeSDK.multiSim(stubTrans)import BlocknativeSdk from 'bnc-sdk'
import Web3 from 'web3'
const web3 = new Web3(window.ethereum)
// create options object
const options = {
dappId: '<YOUR_API_KEY>',
networkId: 4
// un-comment if you would like to log all transaction events
// transactionHandlers: [event => console.log(event.transaction)]
}
// initialize and connect to the api
const blocknative = new BlocknativeSdk(options)
const address = '0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D'
const { emitter, details } = blocknative.account(address)
emitter.on('all', transaction => {
console.log(transaction)
})For detailed documentation head to docs.blocknative.com
For apps that operate on multiple chains at once, you can use the Multichain SDK which provides a simple interface that abstracts away handling multiple WS connections at once and has a new API for subscribing to events.
Currently a transaction hash or account address can be subscribed to for all events. The subscribe method requires an id, chainId and a type and returns an Observable. The Observable that is returned is specific for events on this subscription and on completion or unsubscribing from the observable will automatically unsubscribe within the SDK. Alternatively you can listen on the global transactions Observable at sdk.transactions$.
import Blocknative from 'bnc-sdk'
const blocknative = Blocknative.multichain({ apiKey: '<YOUR_API_KEY>' })
// subscribe to address events
const addressSubscription = blocknative.subscribe({
id: '0x32ee303b76B27A1cd1013DE2eA4513aceB937c72',
chainId: '0x1',
type: 'account'
})
// can listen to the address subscription directly
addressSubscription.subscribe(transaction => console.log(transaction))
// subscribe to transaction events
const transactionSubscription = blocknative.subscribe({
id: '0xbb1af436fd539a6282c6f45ed900abb5ac95ec435367f61fa8815a61bd2a7211',
chainId: '0x1',
type: 'transaction'
})
// can listen to the transaction subscription directly
transactionSubscription.subscribe(transaction => console.log(transaction))
// or can listen for all transaction events on the global transactions$ observable
blocknative.transaction$.subscribe(transaction => console.log(transaction))To stop listening to events on a transaction hash or account address, call the unsubscribe method. If called without a chainId, all networks will unsubscribe from the transaction or address. To only unsubscribe on a particular network, pass in the chainId of that network.
blocknative.unsubscribe({
id: 'transactionHashOrAddress',
chainId: '0x1'
})