What is Hardhat?

• Complete development environment for smart contracts and dApps
• Built around concepts of tasks and plugins
• Customizable and extendable workflows
• Integrated testing, debugging, and deployment tools

Prerequisites

Required Software:

• Node.js and npm - JavaScript runtime environment
• Alchemy Account - Blockchain developer platform

Download Links:

• Node.js: https://nodejs.org/en/download/
• Alchemy: https://www.alchemy.com/

1Create Project Folders

Create separate folders for JavaScript and TypeScript projects:

# Create directories
mkdir Project_JScript
mkdir Project_TSCript
        

2Install Hardhat

# Install Hardhat locally
npm install --save-dev hardhat

# For specific version
npm install --save-dev "hardhat@^2.12.0"

Initialize Hardhat Project

This command brings up the project initialization menu:

• Create a JavaScript project
• Create a TypeScript project
• Create an empty hardhat.config.js

Project Structure

contracts/
scripts/
test/
.gitignore
hardhat.config.js
package.json
README.md
                

contracts/
scripts/
test/
typechain-types/
hardhat.config.ts
tsconfig.json
package.json
               

Configuration Files

JavaScript (hardhat.config.js):

require("@nomicfoundation/hardhat-toolbox");

module.exports = {
  solidity: "0.8.17",
};
        

TypeScript (hardhat.config.ts):

import { HardhatUserConfig } from "hardhat/config";
import "@nomicfoundation/hardhat-toolbox";

const config: HardhatUserConfig = {
  solidity: "0.8.17",
};

export default config;

Compiling Smart Contracts

Expected Output:

Downloading compiler 0.8.17
Compiled 1 Solidity file successfully

Essential Dependencies

Install these modules for comprehensive smart contract testing:

npm install --save-dev @nomicfoundation/hardhat-toolbox
npm install --save-dev @typechain/hardhat --legacy-peer-deps
npm install --save-dev hardhat-gas-reporter --legacy-peer-deps
npm install --save-dev solidity-coverage --legacy-peer-deps

Testing Commands:

npx hardhat test
npx hardhat test test/my-tests.ts

Setting up Local Hardhat Network

This starts a standalone local Hardhat network with:

• 20 test accounts with 10,000 ETH each
• Local blockchain running on localhost:8545
• Automatic mining
• Console logging of all transactions

Deploying to Local Network

JavaScript Deployment:

TypeScript Deployment:

Success Output:

Compiled 1 Solidity file successfully
Lock with 1 ETH and unlock timestamp 1706936380 deployed to 0x5FbDB2315678afecb367f032d93F642f64180aa3
        

Testnet Configuration (Goerli)

Update your hardhat.config.js for Goerli deployment:

require("@nomicfoundation/hardhat-toolbox");

const ALCHEMY_API_KEY = "YOUR_ALCHEMY_KEY";
const GOERLI_PRIVATE_KEY = "YOUR_PRIVATE_KEY";

module.exports = {
  solidity: "0.8.17",
  etherscan: {
    apiKey: "YOUR_ETHERSCAN_API_KEY",
  },
  networks: {
    goerli: {
      url: `https://eth-goerli.alchemyapi.io/v2/${ALCHEMY_API_KEY}`,
      accounts: [GOERLI_PRIVATE_KEY]
    }
  }
};
   

Extracting MetaMask Private Key

1. Click on the identicon in the top right
2. Select the account you'd like to export
3. Click on the menu (three dots) → "Account Details"
4. Click "Export Private Key"
5. Enter your wallet password and click "Confirm"
6. Copy and save your private key securely
7. Click "Done" to close

Deploying to Testnets

Required Setup:

• Alchemy API key
• Etherscan API key
• Private key from MetaMask
• Free ETH from faucet: https://goerlifaucet.com/

Deployment Commands:

# Deploy to Goerli
npx hardhat run scripts/deploy.ts --network goerli

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

# Deploy to Mainnet (be careful!)
npx hardhat run scripts/deploy.ts --network mainnet
       

Sepolia Testnet Setup

const ALCHEMY_API_KEY = "YOUR_SEPOLIA_KEY";
const SEPOLIA_PRIVATE_KEY = "YOUR_PRIVATE_KEY";

module.exports = {
  solidity: "0.8.18",
  networks: {
    sepolia: {
      url: `https://eth-sepolia.g.alchemy.com/v2/${ALCHEMY_API_KEY}`,
      accounts: [SEPOLIA_PRIVATE_KEY]
    }
  }
};
    

OpenZeppelin Integration

Installation:

Sample NFT Contract:

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import "@openzeppelin/contracts/token/ERC721/ERC721.sol";
import "@openzeppelin/contracts/utils/Counters.sol";
import "@openzeppelin/contracts/access/Ownable.sol";

contract MyNFT is ERC721URIStorage, Ownable {
    using Counters for Counters.Counter;
    Counters.Counter private _tokenIds;
    
    constructor() ERC721("MyNFT", "NFT") {}
    
    function mintNFT(address recipient, string memory tokenURI)
        public onlyOwner returns (uint256) {
        _tokenIds.increment();
        uint256 newItemId = _tokenIds.current();
        _mint(recipient, newItemId);
        _setTokenURI(newItemId, tokenURI);
        return newItemId;
    }
}
   

Common Issues & Solutions

🔧 Insufficient Funds Error:

// Reduce locked amount in deploy.ts
const lockedAmount = ethers.utils.parseEther("0.05"); // Instead of 1 ETH

🔧 Missing Menu After Installation:

1. Delete scripts and contracts folders
2. Run npx hardhat --verbose
3. Delete hardhat.config.js
4. Run npx hardhat again

🔧 Debug Deployment Issues:

📚 Additional Resources

Official Documentation:

• Hardhat TypeScript Guide: hardhat.org/hardhat-runner/docs/guides/typescript
• Getting Started: hardhat.org/hardhat-runner/docs/getting-started
• Hardhat Network: hardhat.org/hardhat-network/docs/overview

Key Tools:

• Alchemy: Blockchain API and infrastructure
• Etherscan: Contract verification and exploration
• OpenZeppelin: Secure smart contract library
• MetaMask: Ethereum wallet and gateway