使用Web3.js监听USDT转账报错：TypeError: Cannot read properties of undefined (reading 'on')

我正在使用Node.js和Web3监听以太坊链上我的USDT ERC20钱包地址的交易，希望在USDT转入钱包时实时记录到账金额。以下是我的代码：

const {Web3} = require('web3');
const USDT_ABI = require('erc-20-abi'); 

//My QuickNode WSS endpoint
const wssProviderUrl = 'wss://thrilling-orbital-lake.quiknode.pro/********/';

// Initialize Web3 with WebSocket provider
const web3Client = new Web3(new Web3.providers.WebsocketProvider(wssProviderUrl));

// My wallet address
const yourAddress = '0x***********************';

// USDT contract address on Ethereum
const USDTContractAddress = '0xdAC17F958D2ee523aeeE4C20C7C1dE6e8FcB49aC';

/// Initialize the USDT contract
const USDTContract = new web3Client.eth.Contract(USDT_ABI, USDTContractAddress);

// Subscribe to Transfer events to your address
USDTContract.events.Transfer({ filter: { to: yourAddress } })
  .on('data', (event) => {
    const amount = event.returnValues.value;
    console.log(`Received ${web3Client.utils.fromWei(amount, 'mwei')} USDT to your wallet address!`);
  })
  .on('error', (error) => {
    console.error('Error subscribing to event:', error);
  });

但我持续遇到如下错误：

.on('error', (error) => {
  ^

TypeError: Cannot read properties of undefined (reading 'on')

期望代码能在收到代币时记录交易详情，请问该如何修复？

这个错误的核心原因是USDTContract.events.Transfer()没有返回预期的可订阅对象，通常由以下问题导致，对应修复方法如下：

1. 替换为USDT专属的Transfer事件ABI #

erc-20-abi包的通用ABI可能和USDT合约的实际实现不匹配，直接使用USDT合约的Transfer事件ABI片段即可：

// 移除原有的const USDT_ABI = require('erc-20-abi');
// 手动定义USDT合约的Transfer事件ABI
const USDT_ABI = [
  {
    "anonymous": false,
    "inputs": [
      {
        "indexed": true,
        "internalType": "address",
        "name": "from",
        "type": "address"
      },
      {
        "indexed": true,
        "internalType": "address",
        "name": "to",
        "type": "address"
      },
      {
        "indexed": false,
        "internalType": "uint256",
        "name": "value",
        "type": "uint256"
      }
    ],
    "name": "Transfer",
    "type": "event"
  }
];

2. 等待WebSocket连接就绪后再订阅事件 #

Web3的WebSocket连接是异步初始化的，直接调用订阅会因连接未就绪返回undefined。通过监听连接状态，在连接成功后执行订阅：

const {Web3} = require('web3');

// 手动定义USDT的Transfer事件ABI
const USDT_ABI = [
  {
    "anonymous": false,
    "inputs": [
      {
        "indexed": true,
        "internalType": "address",
        "name": "from",
        "type": "address"
      },
      {
        "indexed": true,
        "internalType": "address",
        "name": "to",
        "type": "address"
      },
      {
        "indexed": false,
        "internalType": "uint256",
        "name": "value",
        "type": "uint256"
      }
    ],
    "name": "Transfer",
    "type": "event"
  }
];

const wssProviderUrl = 'wss://thrilling-orbital-lake.quiknode.pro/********/';
const web3Client = new Web3(new Web3.providers.WebsocketProvider(wssProviderUrl));
const yourAddress = '0x***********************';
const USDTContractAddress = '0xdAC17F958D2ee523aeeE4C20C7C1dE6e8FcB49aC';

// 监听WebSocket连接状态
web3Client.provider.on('connect', () => {
  console.log('WebSocket连接成功');
  // 初始化合约并订阅事件
  const USDTContract = new web3Client.eth.Contract(USDT_ABI, USDTContractAddress);
  USDTContract.events.Transfer({ filter: { to: yourAddress } })
    .on('data', (event) => {
      const amount = event.returnValues.value;
      console.log(`Received ${web3Client.utils.fromWei(amount, 'mwei')} USDT to your wallet address!`);
    })
    .on('error', (error) => {
      console.error('订阅事件出错:', error);
    });
});

web3Client.provider.on('error', (err) => {
  console.error('WebSocket连接失败:', err);
});

3. 适配Web3 v4.x版本的API #

如果使用Web3 v4.x，事件订阅需要通过异步的subscribe方法实现：

const {Web3} = require('web3');

const USDT_ABI = [
  {
    "anonymous": false,
    "inputs": [
      {
        "indexed": true,
        "internalType": "address",
        "name": "from",
        "type": "address"
      },
      {
        "indexed": true,
        "internalType": "address",
        "name": "to",
        "type": "address"
      },
      {
        "indexed": false,
        "internalType": "uint256",
        "name": "value",
        "type": "uint256"
      }
    ],
    "name": "Transfer",
    "type": "event"
  }
];

const wssProviderUrl = 'wss://thrilling-orbital-lake.quiknode.pro/********/';
const web3Client = new Web3(new Web3.providers.WebsocketProvider(wssProviderUrl));
const yourAddress = '0x***********************';
const USDTContractAddress = '0xdAC17F958D2ee523aeeE4C20C7C1dE6e8FcB49aC';

async function subscribeToUSDTTransfers() {
  try {
    const USDTContract = new web3Client.eth.Contract(USDT_ABI, USDTContractAddress);
    const subscription = await USDTContract.subscribe('Transfer', {
      filter: { to: yourAddress }
    });
    subscription.on('data', (event) => {
      const amount = event.returnValues.value;
      console.log(`Received ${web3Client.utils.fromWei(amount, 'mwei')} USDT to your wallet address!`);
    });
    subscription.on('error', (error) => {
      console.error('订阅事件出错:', error);
    });
  } catch (err) {
    console.error('订阅初始化失败:', err);
  }
}

web3Client.provider.on('connect', () => {
  console.log('WebSocket连接成功');
  subscribeToUSDTTransfers();
});

web3Client.provider.on('error', (err) => {
  console.error('WebSocket连接失败:', err);
});

4. 校验地址格式 #

确保yourAddress和USDTContractAddress是有效的以太坊地址（支持全小写或校验和格式），避免因地址格式错误导致订阅逻辑异常。

内容的提问来源于stack exchange，提问作者Anything figures