helloweb3/index.html at main · larryjay007/helloweb3 · GitHub

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<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Hello Web3 DApp</title>
<script src="https://cdn.jsdelivr.net/npm/ethers@5.7.2/dist/ethers.umd.min.js"></script>
<style>
body {
font-family: Arial, sans-serif;
padding: 40px;
}
button {
margin-top: 10px;
}
input {
padding: 5px;
margin-top: 5px;
width: 300px;
}
</style>
</head>
<body>

<h1>Hello Web3 DApp</h1>

<button id="connectButton">Connect Wallet</button>
<p><strong>Connected Wallet:</strong> <span id="walletAddress">Not connected</span></p>

<hr>

<h3>Current Message:</h3>
<p id="currentMessage">No message loaded yet</p>
<button id="getMessage">Get Message</button>

<h3>Update Message:</h3>
<input type="text" id="newMessageInput" placeholder="Enter new message">
<button id="setMessage">Update Message</button>

<script>
const contractAddress = "0xc929CEf83242b17aB7202eDBdaC7F7243Bff4d71";
const contractABI = [
{
"inputs": [{"internalType": "string", "name": "_message", "type": "string"}],
"stateMutability": "nonpayable",
"type": "constructor"
},
{
"inputs": [],
"name": "getMessage",
"outputs": [{"internalType": "string", "name": "", "type": "string"}],
"stateMutability": "view",
"type": "function"
},
{
"inputs": [],
"name": "message",
"outputs": [{"internalType": "string", "name": "", "type": "string"}],
"stateMutability": "view",
"type": "function"
},
{
"inputs": [{"internalType": "string", "name": "_newMessage", "type": "string"}],
"name": "setMessage",
"outputs": [],
"stateMutability": "nonpayable",
"type": "function"
}
];

let provider;
let signer;
let contract;

// Connect wallet
async function connectWallet() {
if (window.ethereum) {
try {
await window.ethereum.request({ method: "eth_requestAccounts" });
provider = new ethers.providers.Web3Provider(window.ethereum);
signer = provider.getSigner();
const userAddress = await signer.getAddress();
document.getElementById("walletAddress").innerText = userAddress;

contract = new ethers.Contract(contractAddress, contractABI, signer);
alert("Wallet connected!");
} catch (err) {
console.error(err);
alert("Wallet connection failed.");
}
} else {
alert("MetaMask is not installed.");
}
}

// Get current message
async function fetchMessage() {
if (!contract) {
alert("Connect wallet first.");
return;
}
try {
const message = await contract.getMessage();
document.getElementById("currentMessage").innerText = message;
} catch (err) {
console.error(err);
alert("Could not fetch message.");
}
}

// Set new message
async function updateMessage() {
if (!contract) {
alert("Connect wallet first.");
return;
}
const newMsg = document.getElementById("newMessageInput").value;
if (!newMsg) {
alert("Enter a message.");
return;
}

try {
const tx = await contract.setMessage(newMsg);
await tx.wait();
alert("Message updated!");
fetchMessage(); // refresh the displayed message
} catch (err) {
console.error(err);
alert("Failed to update message.");
}
}

document.getElementById("connectButton").addEventListener("click", connectWallet);
document.getElementById("getMessage").addEventListener("click", fetchMessage);
document.getElementById("setMessage").addEventListener("click", updateMessage);
</script>

</body>
</html>