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🎤 Weekly presentations🛠️ Hardhat & Web3 Dev Setup

🛠️ Hardhat & Web3 Dev Setup

From User → Builder

This session is about learning how real Web3 developers work.
Not clicking buttons. Writing code that deploys to blockchains.

📚 Essential Resources

🧠 Theory & Core Concepts

Before touching code, you must understand what you are actually doing.

1️⃣ What is Hardhat?

Hardhat is a professional Ethereum development environment.

Why not Remix?

  • Remix is great for demos.
  • It is not how production engineers work.

Hardhat gives you:

  • 🔨 Compilation
    • Solidity → Bytecode (EVM instructions)
    • Solidity → ABI (frontend communication map)
  • 🧪 Testing
    • Local blockchains that reset instantly
  • 🤖 Scripting
    • Automated deployments & interactions using JS/TS

Think of Hardhat as the VS Code + Docker + CI of Web3.

2️⃣ Secrets Management (.env) – Do Not Get Hacked

📖 Learn more: For a detailed guide on environment variables, see Environment Variables

Golden Rule:
🚨 Never commit private keys or API keys to GitHub. Ever.

Why?

  • Bots scan every GitHub commit globally.
  • Leaked key = wallet drained in seconds.

How .env works:

  • Local file with secrets
  • Loaded at runtime into memory
  • Ignored by Git

Analogy:

  • Code = car
  • .env = key
  • You publish the car, not the key

3️⃣ Artifacts – What Are We Deploying?

When Hardhat compiles, it creates an artifacts/ folder.

It contains:

  • 🧾 Bytecode
    • The actual hex code stored on-chain (0x608060...)
  • 🗺️ ABI (Application Binary Interface)
    • JSON description of how to interact with the contract
    • Used by frontends and scripts

ABI = instruction manual
Bytecode = machine

4️⃣ RPC Nodes – Your Gateway to the Blockchain

Your laptop is not a blockchain node.

To interact with Ethereum, you need an RPC Provider:

  • Alchemy
  • Infura
  • Google Cloud Web3

Flow:
Hardhat → RPC Provider → Ethereum Network

🎯 What You Should Gain From This Session

🚀 From User to Developer

  • Metamask → user tool
  • Hardhat → builder tool

🏗️ Professional Dev Setup

  • Node.js & npm
  • Secure key handling
  • Reproducible environments

🧑‍💼 GitHub = Your CV

  • Web3 is open-source by default
  • Recruiters check:
    • Commit history
    • Repo structure
    • Security awareness

🌍 Blockchain “Hello World”

  • Local dev environment
  • Connect to Sepolia testnet
  • Deploy a real smart contract

🧪 Part 1: Project Initialization (10 min)

Prerequisite

node -v

Setup

mkdir tum-web3-week2
cd tum-web3-week2
npm init -y
npm install --save-dev hardhat
npx hardhat init

Choose:

  • TypeScript (recommended)
  • Project root: yes
  • Gitignore: yes

Verify

npx hardhat test

🐙 Part 2: Git & “The CV Builder” (10 min)

Initialize Git

git init
git branch -M main

.gitignore (CRITICAL)

Ensure it includes:

.env
node_modules
coverage

⚠️ If .env is pushed → assume compromise.

First Commit

git add .
git commit -m "feat: initial hardhat setup"

➡️ Create a GitHub repo and push.

🔐 Part 3: Environment Variables & Security (15 min)

📖 Reference: For a comprehensive guide on environment variables in Web3, check out Environment Variables

Install dotenv

npm install dotenv

Get Your Private Key

  1. Metamask → Account Details → Show Private Key

⚠️ Use a throwaway / dev wallet only

Create .env

SEPOLIA_RPC_URL="https://eth-sepolia.g.alchemy.com/v2/YOUR_API_KEY"
PRIVATE_KEY="0x..."

⚙️ Part 4: Hardhat Configuration (10 min)

Edit hardhat.config.ts:

import * as dotenv from "dotenv";
import { HardhatUserConfig } from "hardhat/config";
import "@nomicfoundation/hardhat-toolbox";
 
dotenv.config();
 
const config: HardhatUserConfig = {
  solidity: "0.8.24",
  networks: {
    sepolia: {
      url: process.env.SEPOLIA_RPC_URL,
      accounts: [process.env.PRIVATE_KEY || ""],
    },
  },
};
 
export default config;

Test Connection

npx hardhat console --network sepolia

Inside console:

await ethers.provider.getBlockNumber()

✔️ If it returns a number → success.

🚀 Part 5: First Deployment Script (15 min)

Script Logic

  1. Load contract factory
  2. Send deployment transaction
  3. Wait for confirmation

Run

npx hardhat run scripts/deploy.ts --network sepolia

Verify on Etherscan

  1. Copy deployed address
  2. Open Sepolia Etherscan
  3. Paste address

🎉 You deployed a program to a global distributed network

✅ Final Checklist

  • Hardhat project initialized
  • GitHub repo created & pushed
  • .gitignore includes .env
  • .env contains RPC + private key
  • Sepolia configured in Hardhat
  • Deployment script executed
  • Contract visible on Etherscan

🧠 Final Thought

Web3 development is not about tokens.
It is about engineering discipline, security, and open source credibility.

Welcome to the builder side. 🧱⚡

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