How to deploy smart contracts to different networks in Hardhat?

Deploying smart contracts to different networks in Hardhat requires the following steps:

1. Configure Network Information

Configure target networks in hardhat.config.js:

javascript
networks: {
  sepolia: {
    url: process.env.SEPOLIA_RPC_URL,
    accounts: [process.env.PRIVATE_KEY],
    chainId: 11155111
  },
  mainnet: {
    url: process.env.MAINNET_RPC_URL,
    accounts: [process.env.PRIVATE_KEY],
    chainId: 1
  }
}

2. Create Deployment Script

Create deployment script in scripts/ directory:

javascript
const hre = require("hardhat");

async function main() {
  const Contract = await hre.ethers.getContractFactory("MyContract");
  const contract = await Contract.deploy();
  
  await contract.deployed();
  
  console.log("Contract deployed to:", contract.address);
  
  // Verify contract (optional)
  if (hre.network.name !== "hardhat" && hre.network.name !== "localhost") {
    await contract.deployTransaction.wait(6); // Wait for 6 block confirmations
    await hre.run("verify:verify", {
      address: contract.address,
      constructorArguments: []
    });
  }
}

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

3. Execute Deployment

bash
# Deploy to Sepolia testnet
npx hardhat run scripts/deploy.js --network sepolia

# Deploy to mainnet
npx hardhat run scripts/deploy.js --network mainnet

4. Use Hardhat Ignition (Recommended)

Hardhat Ignition provides a declarative deployment approach:

javascript
const { buildModule } = require("@nomicfoundation/hardhat-ignition/modules");

module.exports = buildModule("MyModule", (m) => {
  const contract = m.contract("MyContract");
  return { contract };
});

Best Practices:

• Use environment variables to manage private keys and RPC URLs
• Wait for sufficient block confirmations after deployment
• Verify contract code on Etherscan
• Save deployment addresses and constructor parameters
• Use multi-sig wallets for mainnet deployment
• Thoroughly test on testnets before deploying to mainnet