Best Practices

Follow these best practices to optimize your use of the UserOpSDK in production applications.

1. Cache AA Wallet Addresses

Calculate and store AA wallet addresses to avoid redundant computation:

// Calculate once and store in your database or local storage
const aaWalletAddress = await builder.getSender();

2. Implement Comprehensive Error Handling

Handle all potential errors gracefully to improve user experience:

try {
  const result = await client.sendUserOperation(builder);
  // Success path
} catch (error) {
  // Categorize and handle different error types
  if (error.message.includes('AA21')) {
    // Handle insufficient funds
  } else if (error.message.includes('AA31')) {
    // Handle paymaster validation error
  } else {
    // Generic error handling
  }
}

3. Gas Estimation

For complex operations, use gas estimation functions to ensure sufficient gas:

// Estimate gas before sending
const gasEstimation = await client.estimateUserOperationGas(builder);
builder.setCallGasLimit(gasEstimation.callGasLimit);
builder.setVerificationGasLimit(gasEstimation.verificationGasLimit);
builder.setPreVerificationGas(gasEstimation.preVerificationGas);

4. Test on Testnet

Always test your implementation on NERO Chain’s testnet before deploying to mainnet:

// Testnet configuration
const NERO_TESTNET_RPC_URL = "https://rpc-testnet.nerochain.io";
const TESTNET_BUNDLER_URL = "https://bundler-testnet.nerochain.io";
const TESTNET_PAYMASTER_URL = "https://paymaster-testnet.nerochain.io";

5. Security

Never store private keys or API keys in client-side code:

// BAD: Hardcoded API key
const PAYMASTER_API_KEY = "your-api-key"; // Don't do this!
 
// GOOD: Load from environment variables on the server
const PAYMASTER_API_KEY = process.env.PAYMASTER_API_KEY;

Additional Resources

For more details and advanced use cases, refer to the following resources:

Error Handling Overview