Handle transactions

Handle EVM transactions in your Wagmi or Vanilla JavaScript dapp. With the SDK, you can:

• Send transactions.
• Track transaction status in real time.
• Estimate gas costs accurately.
• Handle transaction errors gracefully.
• Manage complex transaction patterns.

Use Wagmi

Wagmi provides hooks for sending transactions and tracking their status. The following are examples of sending a basic transaction and an advanced transaction with gas estimation.

Basic transaction

import { parseEther } from "viem"
import { useSendTransaction, useWaitForTransactionReceipt } from "wagmi"

function SendTransaction() {
  const { 
    data: hash,
    error,
    isPending,
    sendTransaction
  } = useSendTransaction()

  const { 
    isLoading: isConfirming,
    isSuccess: isConfirmed 
  } = useWaitForTransactionReceipt({
    hash
  })

  async function handleSend() {
    sendTransaction({
      to: "0x...", 
      value: parseEther("0.1")  // 0.1 ETH
    })
  }

  return (
    <div>
      <button 
        onClick={handleSend}
        disabled={isPending}
      >
        {isPending ? "Confirming..." : "Send 0.1 ETH"}
      </button>

      {hash && (
        <div>
          Transaction Hash: {hash}
          {isConfirming && <div>Waiting for confirmation...</div>}
          {isConfirmed && <div>Transaction confirmed!</div>}
        </div>
      )}

      {error && <div>Error: {error.message}</div>}
    </div>
  )
}

Advanced transaction with gas estimation

import { parseEther } from "viem"
import { 
  useSendTransaction, 
  useWaitForTransactionReceipt,
  useEstimateGas
} from "wagmi"

function AdvancedTransaction() {
  const transaction = {
    to: "0x...",
    value: parseEther("0.1"),
    data: "0x..." // Optional contract interaction data
  }

  // Estimate gas
  const { data: gasEstimate } = useEstimateGas(transaction)

  const { sendTransaction } = useSendTransaction({
    ...transaction,
    gas: gasEstimate,
    onSuccess: (hash) => {
      console.log("Transaction sent:", hash)
    }
  })

  return <button onClick={() => sendTransaction()}>Send with Gas Estimate</button>
}

Use Vanilla JavaScript

You can implement transaction handling directly in Vanilla JavaScript. The following are examples of sending a basic transaction and an advanced transaction with gas estimation.

Basic transaction

async function sendTransaction(recipientAddress, amount) {
  try {
    // Get current account
    const accounts = await ethereum.request({ 
      method: "eth_requestAccounts" 
    });
    const from = accounts[0];

    // Convert ETH amount to wei (hex)
    const value = `0x${(amount * 1e18).toString(16)}`;

    // Prepare transaction
    const transaction = {
      from,
      to: recipientAddress,
      value,
      // Gas fields are optional - MetaMask will estimate
    };

    // Send transaction
    const txHash = await ethereum.request({
      method: "eth_sendTransaction",
      params: [transaction],
    });

    return txHash;
  } catch (error) {
    if (error.code === 4001) {
      throw new Error("Transaction rejected by user");
    }
    throw error;
  }
}

// Track transaction status
function watchTransaction(txHash) {
  return new Promise((resolve, reject) => {
    const checkTransaction = async () => {
      try {
        const tx = await ethereum.request({
          method: "eth_getTransactionReceipt",
          params: [txHash],
        });

        if (tx) {
          if (tx.status === "0x1") {
            resolve(tx);
          } else {
            reject(new Error("Transaction failed"));
          }
        } else {
          setTimeout(checkTransaction, 2000); // Check every 2 seconds
        }
      } catch (error) {
        reject(error);
      }
    };

    checkTransaction();
  });
}

The following is an example implementation of the basic transaction:

<div class="transaction-form">
  <input type="text" id="recipient" placeholder="Recipient Address">
  <input type="number" id="amount" placeholder="Amount in ETH">
  <button onclick="handleSend()">Send ETH</button>
  <div id="status"></div>
</div>

<script>
async function handleSend() {
  const recipient = document.getElementById("recipient").value;
  const amount = document.getElementById("amount").value;
  const status = document.getElementById("status");
  
  try {
    status.textContent = "Sending transaction...";
    const txHash = await sendTransaction(recipient, amount);
    status.textContent = `Transaction sent: ${txHash}`;

    // Watch for confirmation
    status.textContent = "Waiting for confirmation...";
    await watchTransaction(txHash);
    status.textContent = "Transaction confirmed!";
  } catch (error) {
    status.textContent = `Error: ${error.message}`;
  }
}
</script>

Advanced transaction with gas estimation

async function estimateGas(transaction) {
  try {
    const gasEstimate = await ethereum.request({
      method: "eth_estimateGas",
      params: [transaction]
    });
    
    // Add 20% buffer for safety
    return BigInt(gasEstimate) * 120n / 100n;
  } catch (error) {
    console.error("Gas estimation failed:", error);
    throw error;
  }
}

info

See the Provider API reference and JSON-RPC API reference for more information.

Best practices

Follow these best practices when handling transactions.

Transaction security

• Always validate inputs before sending transactions.
• Check wallet balances to ensure sufficient funds.
• Verify addresses are valid.

Error handling

• Handle common errors like user rejection and insufficient funds.
• Provide clear error messages to users.
• Implement proper error recovery flows.
• Consider network congestion in gas estimates.

User experience

• Display clear loading states during transactions.
• Show transaction progress in real time.
• Provide detailed transaction information.

Common errors

Error code	Description	Solution
4001	User rejected transaction	Show a retry option and a clear error message.
-32603	Insufficient funds	Check the balance before sending a transaction.
-32000	Gas too low	Increase the gas limit or add a buffer to the estimation.
-32002	Request already pending	Prevent multiple concurrent transactions.

Next steps

See the following guides to add more functionality to your dapp:

• Authenticate users
• Manage networks
• Interact with smart contracts