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Setup Hardhat

Hardhat is a development environment for Ethereum software. It helps developers compile, deploy, test, and debug their Ethereum applications. This guide will help you set up Hardhat for developing on SKALE.

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Prerequisites

  • Node.js (v16 or higher) installed
  • npm or yarn package manager
  • Basic knowledge of JavaScript/TypeScript

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Step 1: Create a New Project

Create a new directory and initialize a Node.js project: 
mkdir my-skale-project
cd my-skale-project
npm init -y

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Step 2: Install Hardhat

Install Hardhat and its dependencies: 
npm install --save-dev hardhat @nomicfoundation/hardhat-toolbox
The @nomicfoundation/hardhat-toolbox package includes all commonly used plugins and tools for Hardhat development.

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Step 3: Initialize Hardhat

Initialize a Hardhat project: 
npx hardhat init
Select “Create a JavaScript project” (or TypeScript if preferred) and follow the prompts.

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Step 4: Configure Hardhat for SKALE

Update your hardhat.config.js (or hardhat.config.ts) file: 
require("@nomicfoundation/hardhat-toolbox");

/** @type import('hardhat/config').HardhatUserConfig */
module.exports = {
  solidity: {
    version: "0.8.19",
    settings: {
      optimizer: {
        enabled: true,
        runs: 200,
      },
    },
  },
  networks: {
    skale_testnet: {
      url: "https://testnet.skalenodes.com/v1/juicy-low-small-testnet",
      accounts: process.env.PRIVATE_KEY ? [process.env.PRIVATE_KEY] : [],
      chainId: 1444673419,
    },
    skale_mainnet: {
      url: "https://mainnet.skalenodes.com/v1/elated-tan-skat",
      accounts: process.env.PRIVATE_KEY ? [process.env.PRIVATE_KEY] : [],
      chainId: 2046399126,
    },
  },
  etherscan: {
    apiKey: {
      skale_testnet: "your-api-key", // Not required for Blockscout
    },
    customChains: [
      {
        network: "skale_testnet",
        chainId: 1444673419,
        urls: {
          apiURL: "https://juicy-low-small-testnet.explorer.testnet.skalenodes.com/api",
          browserURL: "https://juicy-low-small-testnet.explorer.testnet.skalenodes.com",
        },
      },
    ],
  },
};
Replace the RPC URLs with your specific SKALE Chain endpoint. You can find SKALE Chain endpoints in the SKALE Portal.

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Step 5: Install OpenZeppelin Contracts

Install OpenZeppelin Contracts: 
npm install @openzeppelin/contracts

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Step 6: Create Environment File

Create a .env file in your project root: 
PRIVATE_KEY=your-private-key-here
Never commit your .env file to version control. Add it to your .gitignore file.
Install dotenv package: 
npm install dotenv
Update your hardhat.config.js to load environment variables: 
require("@nomicfoundation/hardhat-toolbox");
require("dotenv").config();

// ... rest of config

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Step 7: Create a Deployment Script

Create a deployment script in scripts/deploy.js: 
const hre = require("hardhat");

async function main() {
  const MyContract = await hre.ethers.getContractFactory("MyContract");
  const myContract = await MyContract.deploy();

  await myContract.waitForDeployment();

  console.log("Contract deployed to:", await myContract.getAddress());
}

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

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Step 8: Compile Contracts

Compile your contracts: 
npx hardhat compile

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Step 9: Run Tests

Run your tests: 
npx hardhat test

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Step 10: Deploy to SKALE

Deploy your contract to SKALE: 
npx hardhat run scripts/deploy.js --network skale_testnet

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SKALE-Specific Considerations

When deploying to SKALE with Hardhat:
  1. Transaction Type: Hardhat automatically handles transaction types, but ensure your Hardhat version supports legacy transactions if needed
  2. Gas Configuration: SKALE has zero gas fees, but you still need sFUEL for transactions: 
    networks: {
  skale_testnet: {
    url: "...",
    accounts: [...],
    gasPrice: 0, // SKALE has zero gas fees
  },
},
  3. Contract Verification: Verify contracts using Hardhat’s verify plugin: 
    npx hardhat verify --network skale_testnet <CONTRACT_ADDRESS> <CONSTRUCTOR_ARGS>

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Project Structure

Your Hardhat project should look like this: 
my-skale-project/
├── contracts/     # Smart contracts
├── scripts/       # Deployment scripts
├── test/          # Test files
├── hardhat.config.js
├── .env
└── package.json

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Next Steps

Now that Hardhat is set up, you can: