如何使用web3 js在uniswap上交换令牌

问题描述

我正在尝试使用uniswap合同方法，使用Metamask钱包中的eth来简单地将eth交换为令牌。 Uniswap合约方法是：

function swapExactETHForTokens(uint amountOutMin,address[] calldata path,address to,uint deadline)
  external
  payable
  returns (uint[] memory amounts);

我的天真印象是应该看起来像这样，但是我确定我缺少几个关键部分（例如签署交易，使用适当的回调方法），并且找不到完整的示例。一个完整的工作示例应如何显示？

const ETHaddress = "0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2"
const DAIaddress = "0x6b175474e89094c44da98b954eedeac495271d0f"

const routerContract = new web3.eth.Contract(
                  UniswapRouteraBI,"0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D"
                );

routerContract.methods.swapExactETHForTokens(500,[ETHaddress,DAIaddress],myWalletAddress,someDeadline)
.send(from: myWalletAddress,value: "1000000000000")

解决方法

首先你应该像下面这样登录你的eth账户

const keystore = fs.readFileSync("your keystore path","utf8");
var activeAccount = web3.eth.accounts.decrypt(keystore,password);

现在您可以签署和广播您的交易。您必须对交换消息进行编码并添加 tx 的数据字段。不要错过多少想用代币交换的 eth 数量。

var swap = UniswapV2Router02Contract.methods.swapExactETHForTokens(amountOutMin,[WETH[activeChain].address,token.address],activeAccount.address,timeStamp)
var encodedABI = swap.encodeABI()

var tx = {
    from: activeAccount.address,to: UniswapV2RouterAddress,gas: 200000,data: encodedABI,value: ethAmount
  };

var signedTx = await activeAccount.signTransaction(tx)

web3.eth.sendSignedTransaction(signedTx.rawTransaction)
.on('transactionHash',function(hash){

})
.on('confirmation',function(confirmationNumber,receipt){

})
.on('receipt',function(receipt){

})
.on('error',function(error,receipt) { // If the transaction was rejected by the network with a receipt,the second parameter will be the receipt.
    console.error("Error:",error,"Receipt:",receipt)
});

,

您可以在 pancakeswap.finance 上查看此工作示例以进行购买： https://github.com/religion-counter/onlyone/blob/main/helper-scripts/buy-onlyone-pancakeswap.js

// Helper script that buys ONLYONE token from a specified address specified on text file SPECIFY_ACCOUNTS_YOU_WANT_TO_BUY_FOR_HERE.json
// The amount is specified with 'originalAmountToBuyWith' variable in the source
// The JSON file should have an array with objects with 'address' field and 'privateKey' field.
// Buys ONLYONE for ${bnbAmount} BNB from pancakeswap for address ${targetAccounts[targetIndex].address}
// targetIndex is passed as an argument: process.argv.splice(2)[0]

var fs = require('fs')
var Tx = require('ethereumjs-tx').Transaction;
var Web3 = require('web3')
var Common = require('ethereumjs-common').default;

var web3 = new Web3(new Web3.providers.HttpProvider('https://bsc-dataseed.binance.org/'))
var BSC_FORK = Common.forCustomChain(
    'mainnet',{
        name: 'Binance Smart Chain Mainnet',networkId: 56,chainId: 56,url: 'https://bsc-dataseed.binance.org/'
    },'istanbul',);

// SPECIFY_THE_AMOUNT_OF_BNB_YOU_WANT_TO_BUY_FOR_HERE
var originalAmountToBuyWith = '0.007' + Math.random().toString().slice(2,7);
var bnbAmount = web3.utils.toWei(originalAmountToBuyWith,'ether');

var targetAccounts = JSON.parse(fs.readFileSync('SPECIFY_ACCOUNTS_YOU_WANT_TO_BUY_FOR_HERE.json','utf-8'));

var targetIndex = Number(process.argv.splice(2)[0]);
var targetAccount = targetAccounts[targetIndex];

console.log(`Buying ONLYONE for ${originalAmountToBuyWith} BNB from pancakeswap for address ${targetAccount.address}`);

var res = buyOnlyone(targetAccounts[targetIndex],bnbAmount);
console.log(res);

async function buyOnlyone(targetAccount,amount) {

    var amountToBuyWith = web3.utils.toHex(amount);
    var privateKey = Buffer.from(targetAccount.privateKey.slice(2),'hex')  ;
    var abiArray = JSON.parse(JSON.parse(fs.readFileSync('onlyone-abi.json','utf-8')));
    var tokenAddress = '0xb899db682e6d6164d885ff67c1e676141deaaa40'; // ONLYONE contract address
    var WBNBAddress = '0xbb4cdb9cbd36b01bd1cbaebf2de08d9173bc095c'; // WBNB token address

    // var onlyOneWbnbCakePairAddress = '0xd22fa770dad9520924217b51bf7433c4a26067c2';
    // var pairAbi = JSON.parse(fs.readFileSync('cake-pair-onlyone-bnb-abi.json','utf-8'));
    // var pairContract = new web3.eth.Contract(pairAbi,onlyOneWbnbCakePairAddress/*,{from: targetAccount.address}*/);
    var amountOutMin = '100' + Math.random().toString().slice(2,6);
    var pancakeSwapRouterAddress = '0x10ed43c718714eb63d5aa57b78b54704e256024e';

    var routerAbi = JSON.parse(fs.readFileSync('pancake-router-abi.json','utf-8'));
    var contract = new web3.eth.Contract(routerAbi,pancakeSwapRouterAddress,{from: targetAccount.address});
    var data = contract.methods.swapExactETHForTokens(
        web3.utils.toHex(amountOutMin),[WBNBAddress,tokenAddress],targetAccount.address,web3.utils.toHex(Math.round(Date.now()/1000)+60*20),);

    var count = await web3.eth.getTransactionCount(targetAccount.address);
    var rawTransaction = {
        "from":targetAccount.address,"gasPrice":web3.utils.toHex(5000000000),"gasLimit":web3.utils.toHex(290000),"to":pancakeSwapRouterAddress,"value":web3.utils.toHex(amountToBuyWith),"data":data.encodeABI(),"nonce":web3.utils.toHex(count)
    };

    var transaction = new Tx(rawTransaction,{ 'common': BSC_FORK });
    transaction.sign(privateKey);

    var result = await web3.eth.sendSignedTransaction('0x' + transaction.serialize().toString('hex'));
    console.log(result)
    return result;
}

如果有兴趣，您也可以为存储库做出贡献。