Web3js
將交易發送到智能合約時出錯
我有這個問題，我正在做一個關於如何通過 web3 與區塊鏈互動的教程，我從區塊鏈得到一些響應，但問題是當我嘗試發送交易或嘗試與智能合約互動時。當我點擊發送按鈕時出現錯誤：未擷取的 ReferenceError：myContract 未定義，但是，在此之前程式碼執行良好，顯示數據並且一切看起來都很好，但是當我點擊錯誤並且函式沒有不行。
我正在處理 localhost、remix 和 metamask。未部署 ganache/rpc/geth。只想從 HTML 文件連接到區塊鏈。
這是我的完整程式碼：
<!DOCTYPE HTML> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <meta http-equiv="X-UA-Compatible" content="ie=edge"> <title>Testing web3 connection</title> <link rel="stylesheet" type="text/css" href="main.css"> <script src="./node_modules/web3/dist/web3.min.js"></script> <script src="abi.js"></script> </head> <body> <div class="container"> <h1>Web 3 test</h1> Welcome to our token creator site <p></p> <p></p> Your address is:<strong><div id="mywallet"></div></strong> <p></p> <p></p> Contract Owner: <br><strong><div id="owner"></div></strong> <p></p> Total Supply: <br><strong><div id="total"></div></strong> <p></p> <input type="text" id="name"> <p></p> <input type="text" id="amount"> <p></p> <button id="sending">Send</button> <strong><div id="txStatus"></div></strong> </div> <script src="https://code.jquery.com/jquery-3.4.1.slim.min.js"></script> <script> window.addEventListener('load', async () => { if (window.ethereum) { window.web3 = new Web3(ethereum); try { await ethereum.enable(); if (web3) { switch (web3.version.network) { case '1': console.log('This is mainnet'); break; case '2': console.log('This is the deprecated Morden test network.'); break; case '3': console.log('This is the ropsten test network.'); break; case '4': console.log('This is the Rinkeby test network.'); break; case '42': console.log('This is the Kovan test network.'); break; default: console.log('This is an unknown network.'); } var desiredNetwork = 4; if (web3.version.network != desiredNetwork){ // alert('Please switch to main network.'); } web3.eth.getAccounts(function(err, accounts){ if (err != null) { console.log(err) } else if (accounts.length === 0){ console.log('MetaMask is locked'); alert('Please connect to MetaMask'); } else { console.log('MetaMask is unlocked') } }); //This data is showed in the test file on localhost, so I got response from blockchain account = await web3.eth.getAccounts(); $('#mywallet').html(account); var myContract = new web3.eth.Contract(myABI, '0xf65eFbCA9C36299AD50CF177bdE261973661174D'); var owner = await myContract.methods.owner().call(); $('#owner').html(owner); //End data response } } catch (error) { } } // Legacy dapp browsers... else if (window.web3) { window.web3 = new Web3(web3.currentProvider); } // Non-dapp browsers... else { console.log('Non-Ethereum browser detected. You should consider trying MetaMask or Trust Wallet!'); } }); $("#sending").click(function() { //when I clicked here an error appears => Uncaught ReferenceError: myContract is not defined var id = $('#name').val(); var amount = $('#amount').val(); myContract.methods.addName(id , amount, account).send(); }); </script>我已經測試了一個星期，我看不到我的錯誤。
通過 web3 + java 執行此操作的正確方法：
//Check if the object is definied if (typeof web3 !== 'undefined') { web3 = new Web3(web3.currentProvider); } else { // set the provider you want from Web3.providers web3 = new Web3(new Web3.providers.HttpProvider("http://localhost:8545")); } //Init my constant const contractAddress = 'MY CONTRACT ADDRESS HERE'; // I created my contract instance const myContract = new web3.eth.Contract(myABI, 'MY CONTRACT ADDRESS'); //As I'm working with promises, I need an async function //to get the blockchain data and to interact with blockchain async function getDetais() { //maybe there is a better option that getaccount, this works for me const account = await web3.eth.getAccounts(); $('#mywallet').html(account); const balance = await web3.eth.getBalance(account[0]); const balanceinETH = balance/1000000000000000000; $('#mybalance').html(balanceinETH +' ETH'); const ContractOwner = await myContract.methods.owner().call(); $('#owner').html(ContractOwner); const BaseURL = await myContract.methods.url().call(); $('#BaseURL').html(BaseURL); const totalSupply = await myContract.methods.totalSupply().call(); $('#total').html(totalSupply); $("#sending").click(function() { //I need to set up the value of gas inside the send function. See //web3 documentation to know more about it myContract.methods.createToken($("#name").val(), $("#fdate").val()).send({from: account[0], to: contractAddress, gas: 2100000}); }); } //I call my function getDetais();使用此程式碼，您可以非常輕鬆地與區塊鏈智能合約進行互動。
您必須將發送功能轉移到包含 myContract 實例的主文件（您在其中部署/分配了包含您的 abis 的契約）。您可以通過將 id 分配給前端的標籤來做到這一點。您最好嘗試 REACTJS，它將是有用。