Simple UniswapV2 Event Indexer

UniV2SwapIndexer.js

const ethers = require("ethers");

const provider = new ethers.providers.WebSocketProvider(
    "wss://mainnet.infura.io/ws/v3/<RPC-KEY-HERE>"
)

const swapHistory = {}

filter = {
    address: ["0xE1De07566cEb19D2e45B60B491776aB74C9b8d7A"],  //token address
    topics: [
        "0xd78ad95fa46c994b6551d0da85fc275fe613ce37657fb8d5e3d130840159d822"  //event address
    ]
}

const decodeData = (data) => {
    return ethers.utils.defaultAbiCoder.decode(
        ['address', 'uint256', 'uint256', 'uint256', 'uint256', 'address'],
        ethers.utils.hexDataSlice(data, 4)
    )
}

const decodeIface = (data) => {
    const iface = new ethers.utils.Interface([ "event Swap(address indexed sender, uint256 amount0In, uint256 amount1In, uint256 amount0Out, uint256 amount1Out, address indexed to)" ]);
    const event = iface.parseLog(data);
    return event;
}

provider.on(filter, (e) => {
    //console.log(e)
    let swapDat = decodeIface(e)
    //console.log(swapDat)
    
    let swapObj = {
        "txnHash": e.transactionHash,
        "sender": swapDat.args[0],
        "amount0In": ethers.utils.formatEther(parseInt(swapDat.args[1]._hex).toString()),
        "amount1In": ethers.utils.formatEther(parseInt(swapDat.args[2]._hex).toString()),
        "amount0Out": ethers.utils.formatEther(parseInt(swapDat.args[3]._hex).toString()),
        "amount1Out": ethers.utils.formatEther(parseInt(swapDat.args[4]._hex).toString()),
        "to": swapDat.args[5],
    }
    //console.log(swapObj);
    
    swapHistory[e.transactionHash] = swapObj;
})