ConsultarEventosPublic.js

//Programa WEB3.js para Consultar el evento 'Transfer' del Contrato ERC-20 de Uniswap UNI
//los ultimos 10 bloques de la cadena
//Se usa el metodo 
//Se consultan los eventos pasados getPastEvents

//comandos npm
//npm i web3
//para ejecutar: node ConsultaEventos.js


const Web3 = require('web3')
const web3 = new Web3('https://mainnet.infura.io/v3/xx83eef769bc45ccaed69d43a03d6cxx')

// eventos de UNISWAP
const abi = [{"inputs":[{"internalType":"address","name":"account","type":"address"},{"internalType":"address","name":"minter_","type":"address"},{"internalType":"uint256","name":"mintingAllowedAfter_","type":"uint256"}],"payable":false,"stateMutability":"nonpayable","type":"constructor"},{"anonymous":false,"inputs":[{"indexed":true,"internalType":"address","name":"owner","type":"address"},{"indexed":true,"internalType":"address","name":"spender","type":"address"},{"indexed":false,"internalType":"uint256","name":"amount","type":"uint256"}],"name":"Approval","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"internalType":"address","name":"delegator","type":"address"},{"indexed":true,"internalType":"address","name":"fromDelegate","type":"address"},{"indexed":true,"internalType":"address","name":"toDelegate","type":"address"}],"name":"DelegateChanged","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"internalType":"address","name":"delegate","type":"address"},{"indexed":false,"internalType":"uint256","name":"previousBalance","type":"uint256"},{"indexed":false,"internalType":"uint256","name":"newBalance","type":"uint256"}],"name":"DelegateVotesChanged","type":"event"},{"anonymous":false,"inputs":[{"indexed":false,"internalType":"address","name":"minter","type":"address"},{"indexed":false,"internalType":"address","name":"newMinter","type":"address"}],"name":"MinterChanged","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"internalType":"address","name":"from","type":"address"},{"indexed":true,"internalType":"address","name":"to","type":"address"},{"indexed":false,"internalType":"uint256","name":"amount","type":"uint256"}],"name":"Transfer","type":"event"},{"constant":true,"inputs":[],"name":"DELEGATION_TYPEHASH","outputs":[{"internalType":"bytes32","name":"","type":"bytes32"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"DOMAIN_TYPEHASH","outputs":[{"internalType":"bytes32","name":"","type":"bytes32"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"PERMIT_TYPEHASH","outputs":[{"internalType":"bytes32","name":"","type":"bytes32"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"internalType":"address","name":"account","type":"address"},{"internalType":"address","name":"spender","type":"address"}],"name":"allowance","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"internalType":"address","name":"spender","type":"address"},{"internalType":"uint256","name":"rawAmount","type":"uint256"}],"name":"approve","outputs":[{"internalType":"bool","name":"","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"internalType":"address","name":"account","type":"address"}],"name":"balanceOf","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"internalType":"address","name":"","type":"address"},{"internalType":"uint32","name":"","type":"uint32"}],"name":"checkpoints","outputs":[{"internalType":"uint32","name":"fromBlock","type":"uint32"},{"internalType":"uint96","name":"votes","type":"uint96"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"decimals","outputs":[{"internalType":"uint8","name":"","type":"uint8"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"internalType":"address","name":"delegatee","type":"address"}],"name":"delegate","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"internalType":"address","name":"delegatee","type":"address"},{"internalType":"uint256","name":"nonce","type":"uint256"},{"internalType":"uint256","name":"expiry","type":"uint256"},{"internalType":"uint8","name":"v","type":"uint8"},{"internalType":"bytes32","name":"r","type":"bytes32"},{"internalType":"bytes32","name":"s","type":"bytes32"}],"name":"delegateBySig","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"internalType":"address","name":"","type":"address"}],"name":"delegates","outputs":[{"internalType":"address","name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"internalType":"address","name":"account","type":"address"}],"name":"getCurrentVotes","outputs":[{"internalType":"uint96","name":"","type":"uint96"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"internalType":"address","name":"account","type":"address"},{"internalType":"uint256","name":"blockNumber","type":"uint256"}],"name":"getPriorVotes","outputs":[{"internalType":"uint96","name":"","type":"uint96"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"minimumTimeBetweenMints","outputs":[{"internalType":"uint32","name":"","type":"uint32"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"internalType":"address","name":"dst","type":"address"},{"internalType":"uint256","name":"rawAmount","type":"uint256"}],"name":"mint","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"mintCap","outputs":[{"internalType":"uint8","name":"","type":"uint8"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"minter","outputs":[{"internalType":"address","name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"mintingAllowedAfter","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"name","outputs":[{"internalType":"string","name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"internalType":"address","name":"","type":"address"}],"name":"nonces","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"internalType":"address","name":"","type":"address"}],"name":"numCheckpoints","outputs":[{"internalType":"uint32","name":"","type":"uint32"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"internalType":"address","name":"owner","type":"address"},{"internalType":"address","name":"spender","type":"address"},{"internalType":"uint256","name":"rawAmount","type":"uint256"},{"internalType":"uint256","name":"deadline","type":"uint256"},{"internalType":"uint8","name":"v","type":"uint8"},{"internalType":"bytes32","name":"r","type":"bytes32"},{"internalType":"bytes32","name":"s","type":"bytes32"}],"name":"permit","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"internalType":"address","name":"minter_","type":"address"}],"name":"setMinter","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"symbol","outputs":[{"internalType":"string","name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"totalSupply","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"internalType":"address","name":"dst","type":"address"},{"internalType":"uint256","name":"rawAmount","type":"uint256"}],"name":"transfer","outputs":[{"internalType":"bool","name":"","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"internalType":"address","name":"src","type":"address"},{"internalType":"address","name":"dst","type":"address"},{"internalType":"uint256","name":"rawAmount","type":"uint256"}],"name":"transferFrom","outputs":[{"internalType":"bool","name":"","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"}]

const address = '0x1f9840a85d5af5bf1d1762f925bdaddc4201f984'

const contractUNI = new web3.eth.Contract(abi, address)

//Este metodo nos va a retornar una promesa con el ultimo bloque minado menos 50 bloques
web3.eth.getBlockNumber()
        .then(n => {
                console.log(n)
                n=n-50
                console.log(n)
        })     
        





//Este metodo nos va a retornar una promesa con eventos pasados
//puedo seleccionar un evento en especial o AllEvents
web3.eth.getBlockNumber()
.then(n => {
    n=n-50
    contractUNI.getPastEvents(
        'Transfer',
        {            
            //Bloque inicial a consultar
            fromBlock: n,
            //Bloque final a consultar
            toBlock: 'latest'
        }
    ).then(events => console.log(events))//como devuelve una promesa usamos then. recibe events    
})





//Este metodo nos va a retornar una promesa con eventos pasados
//puedo seleccionar un evento en especial o AllEvents
//Filtrando por un address
web3.eth.getBlockNumber()
.then(n => {
    n=n-50
    contractUNI.getPastEvents(
        'Transfer',
        {
            //objeto que nos va dar opciones para filtrar
            filter: {_to: '0xfaA318479b7755b2dBfDD34dC306cb28B420Ad12'},
            //Bloque inicial a consultar
            fromBlock: n,
            //Bloque final a consultar
            toBlock: 'latest'
        }
    ).then(events => console.log(events))//como devuelve una promesa usamos then. recibe events    
})