snapshot.js

const {ethers} = require('ethers')
const BN = ethers.BigNumber

const alvinAddress = '0x50DBde932A94b0c23D27cdd30Fbc6B987610c831'
const fromBlock = 14834211
const toBlock = 18032324
const ZERO_ADDRESS = '0x' + '0'.repeat(40)
const rpc = 'https://rpc.xdaichain.com/'


const run = async ( ) => {
    const provider = ethers.getDefaultProvider(rpc)
    const Alvin = new ethers.Contract(
        alvinAddress,
        ['event Transfer(address indexed from, address indexed to, uint256 value)'],
        provider
    )

    const snapshot = {}
    snapshot[ZERO_ADDRESS] = BN.from(0)
    const transferFilter = Alvin.filters.Transfer()

    // 1. get events
    const events = await Alvin.queryFilter(transferFilter, fromBlock, toBlock)
    // 2. for event in events
    for (e in events) {
        // 3. get values from event
        const [from, to, amount] = events[e].args
        // 4.    snapshot[from] -= amount
        snapshot[from] = snapshot[from].sub(amount)      
        // 5. check if the 'to' address has a balance, if not initialise 
        snapshot[to] === undefined ? snapshot[to] = BN.from(0) : null
        // 6. snapshot[to] = vale
        snapshot[to] = snapshot[to].add(amount)
    } 

    console.log(snapshot)
}

run()
.then(() => process.exit(0))
.catch((e) => {
    console.log(e)
    process.exit(1)
})