Cannot use transfer method of ERC20 in map function

Question

I'm trying to iterate through receiver array to send ERC20 token in bulk.

I tried to debug with console.log and seems like the problem is line const tx = await contract.transfer(receiver[i], ammount)

Then I tried running the script outside of the map (as comment) and it's work.

So it must be something with map function (I even tried to console.log(addr === receiver[0]) and it returned true)

Zintea.sol

//SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import "@openzeppelin/contracts/token/ERC20/ERC20.sol";

contract Zintea is ERC20 {
    uint constant _initial_supply = 1000 * (10**18);
    
    constructor() ERC20("Zintea", "ZIN"){
        _mint(msg.sender, _initial_supply);
    }

}

transfer.js

const { ethers } = require('hardhat');

require('dotenv').config();

const CONTRACT_ADDRESS = "0x0e6e60EA3D66421dfBCfB17a6F7f5844059c4948"
const receiver = ["0xAf29CeBfb433925A114f53dE2f347fdD50393443", "0x98Ed91465dD68fBeC574805eC9B6da63eeA380C0"]

async function main() {
    const [signer] = await ethers.getSigners();
    const contract = await ethers.getContractAt("Zintea", CONTRACT_ADDRESS, signer);
    console.log("Balance of sender: ", await contract.balanceOf(signer.getAddress()) / (10**18), "$ZIN" )

    await receiver.map(async (addr) => {
        console.log("Transfering to ", addr)
        const ammount = ethers.utils.parseUnits("10", 18)
        const tx = await contract.transfer(addr, ammount)
        await tx.wait()
        console.log(tx)
        console.log(`Transfered ${10} $ZIN to ${addr} `)
    })

    // Worked
    // console.log("Transfering to ", receiver[0])
    // const ammount = ethers.utils.parseUnits("1", 18)
    // const transfered = await contract.transfer(receiver[1], ammount );
    // await transfered.wait();
    // console.log(`Transfered to ${receiver[0]} `);
    
    console.log("Balance of sender: ", await contract.balanceOf(signer.getAddress()) / (10**18), "$ZIN" )
}

main()
.then(() => process.exit(0))
.catch((error) => {
  console.error(error);
  process.exit(1);
});

Console

Balance of sender:  974 $ZIN
Transfering to  0xAf29CeBfb433925A114f53dE2f347fdD50393443
Transfering to  0x98Ed91465dD68fBeC574805eC9B6da63eeA380C0
Balance of sender:  974 $ZIN

Answer 1

map is not designed to handle promises directly it is not recommended to use it with async/await. Instead, I recommend you to use a for..of loop to iterate through receiver array and execute the transfers.

I also recommend you for better clarity to rename receiver to receivers

  for (const receiver of receivers) {
    console.log("Transfering to ", receiver);
    const amount = ethers.utils.parseUnits("10", 18);
    const tx = await contract.transfer(receiver, amount);
    await tx.wait();
    console.log(tx);
    console.log(`Transfered ${10} $ZIN to ${receiver}`);
  }