实际上，我正在尝试编写一个简单的前端智能合约，它从用户那里获取一个值，并将其保存在智能合约的变量中。我项目的index.html部分是
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>Example</title>
<!-- Bootstrap -->
<link href="css/bootstrap.min.css" rel="stylesheet">
</head>
<body>
<div id="message"></div>
<form method="POST">
<div><input id= "message" name = "message" type= "text">
</div>
<div>
<button type="button" id="register">Register</button>
</div>
</div>
</form>
<script src="js/bootstrap.min.js"></script>
<script src="js/web3.min.js"></script>
<script src="js/truffle-contract.js"></script>
<script src="js/app.js"></script>
</body>
</html>
app.js是
App = {
web3Provider: null,
contracts: {},
account: '0x0',
init: function() {
return App.initWeb3();
},
initWeb3: function() {
if (typeof web3 !== 'undefined') {
// If a web3 instance is already provided by Meta Mask.
App.web3Provider = web3.currentProvider;
web3 = new Web3(web3.currentProvider);
} else {
// Specify default instance if no web3 instance provided
App.web3Provider = new Web3.providers.HttpProvider('http://localhost:7545');
web3 = new Web3(App.web3Provider);
}
return App.initContract();
},
initContract: function() {
$.getJSON("HelloWorld.json", function(hello) {
// Instantiate a new truffle contract from the artifact
App.contracts.HelloWorld = TruffleContract(hello);
// Connect provider to interact with contract
App.contracts.HelloWorld.setProvider(App.web3Provider);
return App.bindEvents();
});
},
bindEvents: function() {
$(document).on('click', '#register', function(){ var msg = $('#message').val(); App.handleMessage(msg); });
},
handleMessage: function(msg){
var hwinstance;
App.contracts.HelloWorld.deployed().then(function(instance) {
hwinstance = instance;
return hwinstance.setMessage(msg);
}).then( function(result){
if(result.receipt.status == '0x01')
alert("successfully")
else
alert("failed due to revert")
}).catch( function(err){
alert("failed")
})
}
};
$(function() {
$(window).load(function() {
App.init();
console.log('starting app.js');
});
});
我写的智能合约代码是
pragma solidity 0.5.16;
contract HelloWorld {
string private message = "hello world";
function getMessage() public view returns(string memory) {
return message;
}
function setMessage(string memory newMessage) public {
message = newMessage;
}
}
当我运行命令truffle complex和truffle migrate时，它没有显示任何错误，但当我运行"npm run dev"时，页面显示"；无法获取/"；。
我不明白错误在哪里。请帮忙！
有没有其他方法可以将前端连接到智能合约？
您的本地服务器找不到您的页面，原因可能是它位于错误的目录中，或者本地服务器尚未安装。运行npm install --save-dev lite-server。在package.json中，你应该有类似的东西
"script": {
"dev": "lite-server",
...
}
将index.html和App.js移动到您在项目根目录创建的src/目录中。再次运行npm run dev进行检查。它应该起作用。如果你对一个易于使用的带有react的松露盒子感兴趣，我开发了一个带有react+Material UI的松露盒。看看这里https://github.com/rouftom/truffle-react-material