Smartcontract multicall

README.md

Install: https://github.com/makerdao/multicall.js

yarn add @makerdao/multicall

multicall.js

// node scripts_local/multicall/multicall.js
require("dotenv").config();
const { aggregate, createWatcher } = require("@makerdao/multicall");

// https://github.com/makerdao/multicall
let config = {
  rpcUrl: "https://bsc-dataseed1.binance.org:443",
  multicallAddress: "0x41263cba59eb80dc200f3e2544eda4ed6a90e76c",
  interval: 1000
};

// Custom config. Default is BSC mainnet
const initConfig = (rpcUrl, multicallAddress, interval = config.interval) => {
  config = { rpcUrl, multicallAddress, interval };
};

// Init watcher with your calls
// return watcher
const initWatcher = (cb) => {
  const watcher = createWatcher(
    [
      {
        call: [
          "getEthBalance(address)(uint256)",
          "0x000000000000000000000000000000000000dead"
        ],
        returns: [["BNB_BALANCE", val => val / 10 ** 18]]
      },
      {
        target: "0x55d398326f99059ff775485246999027b3197955",
        call: ["balanceOf(address)(uint256)", "0x000000000000000000000000000000000000dead"],
        returns: [["BALANCE_OF_USDT_DEAD", val => val / 10 ** 18]]
      },
      // https://docs.chain.link/docs/binance-smart-chain-addresses/
      {
        target: "0x0567F2323251f0Aab15c8dFb1967E4e8A7D42aeE",
        call: ["latestAnswer()(uint256)"],
        returns: [
          ["PRICE_FEED_BNB_USD", val => val / 10 ** 8]
        ]
      }
    ],
    config
  );

  watcher.subscribe(update => {
    // console.log(`Update: ${update.type} = ${update.value}`);
    if (cb) cb(update.type, update.value);
  });
  return watcher;
};

// Start polling
const start = async (watcher, initialFetchedCb) => {
  watcher.start();
  await watcher.awaitInitialFetch();
  if (initialFetchedCb) initialFetchedCb();
};

// module.exports = {
//   initConfig,
//   initWatcher,
//   start
// };

// Example
const example = async () => {
  const watcher = initWatcher((type, value) => {
    console.log(`Update: ${type} = ${value}`);
  });
  await start(watcher, () => {
    console.log("Initial fetch completed");
  });
  // Get initial data manually
  watcher.batch().subscribe(updates => {
    console.log("Initial data:", updates);
  }).unsub();

};
example().then();