Uniswap V3 / EthersJS: decode mempool swap router swaps

.env

WEBSOCKET_URL=wss://mainnet.infura.io/ws/v3/abc

03_listenMempool.js

const { abi: SwapRouterAbi} = require('@uniswap/v3-periphery/artifacts/contracts/SwapRouter.sol/SwapRouter.json')
const ethers = require("ethers");

const contractInterface = new ethers.utils.Interface(SwapRouterAbi);

require('dotenv').config()
const provider = new ethers.providers.WebSocketProvider(process.env.WEBSOCKET_URL)

const main = async () => {
    provider.on('pending', async (hash) => {
        getTransaction(hash)
    });
};

const delay = (ms) => new Promise(resolve => setTimeout(resolve, ms))
const UNISWAP_ADDRESSES = [
    '0xE592427A0AEce92De3Edee1F18E0157C05861564', // swap router
]

let txIdx = 0
const getTransaction = async (transactionHash) => {
    for (let attempt = 1; attempt <= 3; attempt++) {
        const tx = await provider.getTransaction(transactionHash);
        if (tx) {
            if (UNISWAP_ADDRESSES.includes(tx.to)) {
                txIdx += 1
                const data = tx.data
                decodeTransaction(data, txIdx)
                break
            }
        }
        await delay(1000);
    }
}

const decodeTransaction = (txInput, txIdx, isMulticall = false) => {
    const decodedData = contractInterface.parseTransaction({ data: txInput })

    const functionName = decodedData.name

    const args = decodedData.args
    const params = args.params
    const data = args.data

    logFunctionName(functionName, txIdx, isMulticall)


    if (functionName === 'exactInputSingle') { return logExactInputSingle(params) }

    if (functionName === 'exactOutputSingle') { return logExactOutputSingle(params) }

    if (functionName === 'exactInput') { return logExactInput(params) }

    if (functionName === 'exactOutput') { return logExactOutput(params) }

    if (functionName === 'selfPermit') { return logSelfPermit(args) }

    if (functionName === 'refundETH') { return logRefundETH(args) }

    if (functionName === 'unwrapWETH9') { return logUnwrapWETH9(args) }

    if (functionName === 'multicall') { return parseMulticall(data, txIdx) }

    console.log('ADD THIS FUNCTION:', functionName)
    console.log('decodedData:', decodedData)
}

const logFunctionName = (functionName, txIdx, isMulticall) => {
    if (isMulticall) {
        console.log()
        console.log('-------', `Fn: ${txIdx}`, functionName);
        return
    }

    console.log()
    console.log('======================================================================================')
    console.log('==============================', `Tx: ${txIdx} - ${functionName}`, '==============================')
    console.log('======================================================================================')
}

const parseMulticall = (data, txIdx) => {
    data.forEach((tx, fnIdx) => {
        decodeTransaction(tx, fnIdx, true)
    })
}

const logUnwrapWETH9 = (args) => {
    console.log('amountMinimum:    ', args.amountMinimum)
    console.log('recipient:        ', args.recipient)
}

const logExactInputSingle = (params) => {
    console.log('tokenIn:          ', params.tokenIn)
    console.log('tokenOut:         ', params.tokenOut)
    console.log('fee:              ', params.fee)
    console.log('recipient:        ', params.recipient)
    console.log('deadline:         ', params.deadline)
    console.log('amountIn:         ', params.amountIn)
    console.log('amountOutMinimum: ', params.amountOutMinimum)
    console.log('sqrtPriceLimitX96:', params.sqrtPriceLimitX96)
}

const logExactOutputSingle = (params) => {
    console.log('tokenIn:          ', params.tokenIn)
    console.log('tokenOut:         ', params.tokenOut)
    console.log('fee:              ', params.fee)
    console.log('recipient:        ', params.recipient)
    console.log('deadline:         ', params.deadline)
    console.log('amountOut:        ', params.amountOut)
    console.log('amountInMaximum:  ', params.amountInMaximum)
    console.log('sqrtPriceLimitX96:', params.sqrtPriceLimitX96)
}

const logExactInput = (params) => {
    console.log('path:             ', params.path)
    console.log('recipient:        ', params.recipient)
    console.log('deadline:         ', params.deadline)
    console.log('amountIn:         ', params.amountIn)
    console.log('amountOutMinimum: ', params.amountOutMinimum)
}

const logExactOutput = (params) => {
    console.log('path:             ', params.path)
    console.log('recipient:        ', params.recipient)
    console.log('deadline:         ', params.deadline)
    console.log('amountOut:        ', params.amountOut)
    console.log('amountInMaximum:  ', params.amountInMaximum)
}

const logSelfPermit = (params) => {
    console.log('token:            ', params.token)
    console.log('value:            ', params.value)
    console.log('deadline:         ', params.deadline)
}

const logRefundETH = (params) => {
    console.log('Nothing to log')
}



main()

/*
    node scripts/03_listenMempool.js
*/

package.json

{
  "name": "YouTubeTutorials",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "dependencies": {
    "@uniswap/sdk": "^3.0.3",
    "@uniswap/sdk-core": "^4.0.2",
    "@uniswap/v3-core": "^1.0.1",
    "@uniswap/v3-periphery": "^1.4.3",
    "@uniswap/v3-sdk": "^3.9.0",
    "dotenv": "^16.3.1",
    "ethers": "^5.7.2",
  }
}