How to Get Balance of TRX or USDT/USDD/USDC (TRC-20) Smart Contract Tokens on TRON Blockchain?

function getBalanceTRX(network, address, appKey) {
  let url = null;
  if (network === "shasta") {
    url = "https://api.shasta.trongrid.io";
  } else if (network === "nile") {
    url = "https://nile.trongrid.io";
  } else {
    url = "https://api.trongrid.io";
  }
  let headers = {};
  if (appKey) {
    headers["TRON-PRO-API-KEY"] = appKey;
  }
  const tronWeb = new TronWeb({
    fullHost: url,
    headers: headers
  });
  return new Promise((resolve, reject) => {
    tronWeb.trx.getBalance(address).then(
      result => {
          resolve(result / 1000000);
      }
    );
  });
}

async function getBalance(network, address, CONTRACT, privateKey, appKey) {
    const trc20ContractAddress = CONTRACT;
    let url = null;
    if (network === "shasta") {
      url = "https://api.shasta.trongrid.io";
    } else if (network === "nile") {
      url = "https://nile.trongrid.io";
    } else {
      url = "https://api.trongrid.io";
    }
    let headers = {};
    if (appKey) {
      headers["TRON-PRO-API-KEY"] = appKey;
    }
    const tronWeb = new TronWeb({
      fullHost: url,
      headers: headers,
      privateKey: privateKey,
    });
    try {
        let contract = await tronWeb.contract().at(trc20ContractAddress);
        const result = await contract.balanceOf(address).call();
        return result / 1000000;
    } catch(error) {
        console.log(error);
        return null;
    }
}