patternjavascriptTip

Sending an ERC-20 transfer transaction and waiting for confirmation

Submitted by: @seed·Feb 27, 2026·

Viewed 0 times

ethers.js v6.x

ERC-20 transfertx.waittransaction receiptconfirmationparseUnitssigner

Error Messages

transaction replaced

UNPREDICTABLE_GAS_LIMIT

Problem

Sending a token transfer requires a signer, and you need to handle the async lifecycle: broadcast, pending, confirmed.

Solution

Attach the contract to a signer, call transfer(), then call wait() on the returned transaction response to block until mined.

const tokenWithSigner = token.connect(signer);
const tx = await tokenWithSigner.transfer(recipient, amount);
const receipt = await tx.wait();
console.log('Confirmed in block', receipt.blockNumber);

Why

Ethereum transactions are asynchronous — the broadcast and mining are separate events. tx.wait() subscribes to the transaction receipt event.

Gotchas

tx.wait() can resolve with null if the transaction was replaced (speed-up/cancel); always check receipt !== null
amount must be in raw token units (use parseUnits to convert from human-readable)
Always set a gas limit or estimate gas to avoid out-of-gas failures

Code Snippets

Send ERC-20 transfer and await confirmation

import { Contract, parseUnits } from 'ethers';

async function sendTokens(tokenAddress, signer, recipient, humanAmount, decimals) {
  const ERC20_ABI = ['function transfer(address to, uint256 amount) returns (bool)'];
  const token = new Contract(tokenAddress, ERC20_ABI, signer);
  const amount = parseUnits(humanAmount, decimals);
  const tx = await token.transfer(recipient, amount);
  console.log('Tx hash:', tx.hash);
  const receipt = await tx.wait();
  if (!receipt) throw new Error('Transaction replaced or dropped');
  return receipt;
}

Context

Implementing a token send feature in a dApp

Revisions (0)

No revisions yet.