web3开发：前端开发 ethers.js
web3开发：前端使用ethers.js调用Hello智能合约。
hello.sol 智能合约文件：
// SPDX-License-Identifier: MIT
pragma solidity 0.8.0;
contract Hello {
function greet() external pure returns(string memory) {
return "Hello web3";
}
}
dapp.html 前端文件：
<html>
<head>
<script src="https://cdn.ethers.io/lib/ethers-5.2.umd.min.js" type="text/javascript"></script>
<script src="./contract.js" type="text/javascript"></script>
</head>
<body>
<div style="text-align:center">
<div style="text-align: center; margin-top: 30px;">
<button onclick="connectWallet()">Connect Wallet</button>
<button onclick="runContract()">Run Contract</button>
</div>
<div style="margin-top: 10px;" id="account">Account:</div>
<div style="margin-top:10px;" id="contract">Contract:</div>
</div>
<script type="text/javascript">
async function connectWallet() {
if (typeof window.ethereum === "undefined") {
alert("please install wallet first!");
return;
}
let accounts = await window.ethereum.request({method:'eth_requestAccounts'});
if (accounts.length > 0 ) {
document.getElementById("account").innerText = "Account: " + accounts[0];
}
}
async function runContract() {
if (typeof window.ethereum === "undefined") {
alert("please install wallet first!");
return;
}
let provider = new ethers.providers.Web3Provider(window.ethereum);
let contract = new ethers.Contract(contractAddress, contractAbi, provider.getSigner());
let result = await contract.greet();
document.getElementById("contract").innerText = result;
}
</script>
</body>
</html>
contract.js文件：
const contractAddress = "0x620D0eA50aa8Cae1c3C55006793412272De9E8Ed";
const contractAbi = [
{
"inputs": [],
"name": "greet",
"outputs": [
{
"internalType": "string",
"name": "",
"type": "string"
}
],
"stateMutability": "pure",
"type": "function"
}
];
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