Web3-counter

17-web3-counter/.gitignore

@@ -0,0 +1,5 @@
+node_modules
+.env
+.cache
+coverage
+artifacts

17-web3-counter/README.md

@@ -0,0 +1,199 @@
+# Web3-counter
+
+A full-stack Web3 Counter DApp using **Solidity + Hardhat** for smart contracts and **Next.js + wagmi + RainbowKit** for the frontend.
+
+---
+
+## 🚀 Project Summary
+This project demonstrates:
+- A simple **Counter contract** with increment/decrement
+- **Hardhat** for compile, test, local node, deploy
+- **Next.js frontend** with wallet connection
+- Tailwind CSS styling
+- Deployed & tested on **Sepolia Testnet**
+
+---
+
+## ✅ Prerequisites
+- Node.js **>= 18** (`node -v`)
+- npm (or yarn/pnpm)
+- Git (optional)
+- Browser wallet (MetaMask)
+- (Optional) Alchemy/Infura/QuickNode Sepolia RPC
+- Basic terminal knowledge
+
+---
+## 📜 Smart Contract
+
+**`contracts/Counter.sol`**
+```solidity
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.24;
+
+contract Counter {
+    int256 private _value;
+    event Increment(address indexed caller, int256 newValue);
+    event Decrement(address indexed caller, int256 newValue);
+
+    function current() external view returns (int256) {
+        return _value;
+    }
+
+    function increment() external {
+        _value += 1;
+        emit Increment(msg.sender, _value);
+    }
+
+    function decrement() external {
+        _value -= 1;
+        emit Decrement(msg.sender, _value);
+    }
+}```
+
+## ⚙️ Hardhat Config
+
+*hardhat.config.ts*
+
+```import { HardhatUserConfig } from "hardhat/config";
+import "@nomicfoundation/hardhat-toolbox";
+import * as dotenv from "dotenv";
+dotenv.config();
+
+const SEPOLIA_RPC_URL = process.env.SEPOLIA_RPC_URL || "";
+const PRIVATE_KEY = process.env.PRIVATE_KEY || "";
+
+const config: HardhatUserConfig = {
+  solidity: "0.8.28",
+  networks: {
+    sepolia: {
+      url: SEPOLIA_RPC_URL,
+      accounts: PRIVATE_KEY ? [PRIVATE_KEY] : [],
+      chainId: 11155111,
+    },
+  },
+  etherscan: {
+    apiKey: process.env.ETHERSCAN_API_KEY || "",
+  },
+};
+
+export default config;```
+
+##🔑 Environment Variables 
+```SEPOLIA_RPC_URL=https://eth-sepolia.g.alchemy.com/v2/YOUR_KEY
+PRIVATE_KEY=0xYOUR_PRIVATE_KEY
+ETHERSCAN_API_KEY=YOUR_API_KEY
+```
+
+## 🚀 Deploy Script
+```
+const hre = require("hardhat");
+
+async function main() {
+  const Counter = await hre.ethers.getContractFactory("Counter");
+  const counter = await Counter.deploy();
+  await counter.deployed();
+  console.log("Counter deployed to:", counter.address);
+}
+
+main().catch((error) => {
+  console.error(error);
+  process.exitCode = 1;
+});
+```
+
+## Root package.json
+
+```
+{
+  "name": "17-web3-counter",
+  "version": "1.0.0",
+  "private": true,
+  "type": "module",
+  "scripts": {
+    "compile": "hardhat compile",
+    "test": "hardhat test",
+    "clean": "hardhat clean",
+    "node": "hardhat node",
+    "deploy:local": "hardhat run scripts/deploy.js --network localhost",
+    "deploy:sepolia": "hardhat run scripts/deploy.js --network sepolia"
+  },
+  "devDependencies": {
+    "hardhat": "^2.26.3",
+    "@nomicfoundation/hardhat-toolbox": "^6.1.0",
+    "ts-node": "^10.9.2",
+    "typescript": "^5.9.2",
+    "@types/node": "^18.0.0",
+    "dotenv": "^17.2.2"
+  }
+}
+```
+
+## 🖥️ Frontend Setup
+
+```npx create-next-app@latest frontend --ts
+cd frontend
+npm install @rainbow-me/rainbowkit wagmi viem
+npm install -D tailwindcss postcss autoprefixer
+npx tailwindcss init -p
+```
+
+**frontend/package.json** 
+```
+{
+  "name": "frontend",
+  "version": "0.1.0",
+  "private": true,
+  "scripts": {
+    "dev": "next dev",
+    "build": "next build",
+    "start": "next start",
+    "lint": "next lint"
+  }
+}
+```
+
+
+**frontend/styles/globals.css**
+```
+@tailwind base;
+@tailwind components;
+@tailwind utilities;
+```
+
+## ▶️ Run the Project
+**1. Backend (Hardhat)**
+
+### compile contracts
+```npm run compile```
+
+### run local node
+```npm run node```
+
+### deploy to local node
+```npm run deploy:local```
+
+### deploy to Sepolia
+```npm run deploy:sepolia```
+---
+
+## 2. Frontend (Next.js)
+
+**From frontend/:**
+
+```npm run dev```
+---
+
+```Visit 👉 http://localhost:3000```
+
+## 🛠️ Troubleshooting
+
+- npm error Missing script: dev → Add "dev": "next dev" in frontend/package.json
+
+- EJSONPARSE → Check package.json for trailing commas or invalid JSON
+
+- next is not recognized → Run inside frontend/ and ensure Next.js is installed
+
+- Private key invalid (HH8) → Ensure .env private key is 64 hex chars starting with 0x
+
+- Multiple lockfiles warning → Delete extra package-lock.json so only one remains in frontend/ or root
+

17-web3-counter/cache/solidity-files-cache.json

@@ -0,0 +1,77 @@
+{
+  "_format": "hh-sol-cache-2",
+  "files": {
+    "C:\\Users\\durge\\OneDrive\\Desktop\\dapp-tutorial\\17-web3-counter\\contracts\\Counter.sol": {
+      "lastModificationDate": 1756973223620,
+      "contentHash": "4f3aa084ecca1c753d55fa4f35928fa1",
+      "sourceName": "contracts/Counter.sol",
+      "solcConfig": {
+        "version": "0.8.28",
+        "settings": {
+          "evmVersion": "paris",
+          "optimizer": {
+            "enabled": false,
+            "runs": 200
+          },
+          "outputSelection": {
+            "*": {
+              "*": [
+                "abi",
+                "evm.bytecode",
+                "evm.deployedBytecode",
+                "evm.methodIdentifiers",
+                "metadata"
+              ],
+              "": [
+                "ast"
+              ]
+            }
+          }
+        }
+      },
+      "imports": [],
+      "versionPragmas": [
+        "^0.8.24"
+      ],
+      "artifacts": [
+        "Counter"
+      ]
+    },
+    "C:\\Users\\durge\\OneDrive\\Desktop\\dapp-tutorial\\17-web3-counter\\contracts\\Lock.sol": {
+      "lastModificationDate": 1756972948551,
+      "contentHash": "7eee587c347fe6b1de50c96688cb9477",
+      "sourceName": "contracts/Lock.sol",
+      "solcConfig": {
+        "version": "0.8.28",
+        "settings": {
+          "evmVersion": "paris",
+          "optimizer": {
+            "enabled": false,
+            "runs": 200
+          },
+          "outputSelection": {
+            "*": {
+              "*": [
+                "abi",
+                "evm.bytecode",
+                "evm.deployedBytecode",
+                "evm.methodIdentifiers",
+                "metadata"
+              ],
+              "": [
+                "ast"
+              ]
+            }
+          }
+        }
+      },
+      "imports": [],
+      "versionPragmas": [
+        "^0.8.28"
+      ],
+      "artifacts": [
+        "Lock"
+      ]
+    }
+  }
+}

17-web3-counter/contracts/Counter.sol

@@ -0,0 +1,26 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.24;
+
+
+contract Counter {
+int256 private _value;
+event Increment(address indexed caller, int256 newValue);
+event Decrement(address indexed caller, int256 newValue);
+
+
+function current() external view returns (int256) {
+return _value;
+}
+
+
+function increment() external {
+_value += 1;
+emit Increment(msg.sender, _value);
+}
+
+
+function decrement() external {
+_value -= 1;
+emit Decrement(msg.sender, _value);
+}
+}

17-web3-counter/contracts/Lock.sol

@@ -0,0 +1,34 @@
+// SPDX-License-Identifier: UNLICENSED
+pragma solidity ^0.8.28;
+
+// Uncomment this line to use console.log
+// import "hardhat/console.sol";
+
+contract Lock {
+    uint public unlockTime;
+    address payable public owner;
+
+    event Withdrawal(uint amount, uint when);
+
+    constructor(uint _unlockTime) payable {
+        require(
+            block.timestamp < _unlockTime,
+            "Unlock time should be in the future"
+        );
+
+        unlockTime = _unlockTime;
+        owner = payable(msg.sender);
+    }
+
+    function withdraw() public {
+        // Uncomment this line, and the import of "hardhat/console.sol", to print a log in your terminal
+        // console.log("Unlock time is %o and block timestamp is %o", unlockTime, block.timestamp);
+
+        require(block.timestamp >= unlockTime, "You can't withdraw yet");
+        require(msg.sender == owner, "You aren't the owner");
+
+        emit Withdrawal(address(this).balance, block.timestamp);
+
+        owner.transfer(address(this).balance);
+    }
+}

17-web3-counter/frontend/.gitignore

@@ -0,0 +1,41 @@
+# See https://help.github.com/articles/ignoring-files/ for more about ignoring files.
+
+# dependencies
+/node_modules
+/.pnp
+.pnp.*
+.yarn/*
+!.yarn/patches
+!.yarn/plugins
+!.yarn/releases
+!.yarn/versions
+
+# testing
+/coverage
+
+# next.js
+/.next/
+/out/
+
+# production
+/build
+
+# misc
+.DS_Store
+*.pem
+
+# debug
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+.pnpm-debug.log*
+
+# env files (can opt-in for committing if needed)
+.env*
+
+# vercel
+.vercel
+
+# typescript
+*.tsbuildinfo
+next-env.d.ts