前言

web3.js文档
http://web3js.readthedocs.io/en/1.0/

前面的文章也提到了，使用web3.js可以与以太坊进行互动。这篇文章的主要内容如下：

1. 解决web3.js版本问题

2.使用web3.js查询以太币及代币余额，以及进行以太币和代币转账

1.web3.js版本问题

现在使用npm install web3安装的web3.js，会发现node_modules中的web3文件夹中，没有dist文件夹，而查看package.json内容如下：

{"name": "111","version": "1.0.0","description": "","main": "index.js","scripts": {"test": "echo \"Error: no test specified\" && exit 1"},"author": "","license": "ISC","dependencies": {"web3": "^1.0.0-beta.34"}}

会发现web3的版本为"^1.0.0-beta.34"。

官方文档有这么一句话：

大意是这篇文档还在补全中，并且1.0版本的包还没放出。如果要查看当前的0.x.x版本的文档，请戳这里https://github.com/ethereum/wiki/wiki/JavaScript-API。我估计这是web3文件夹没有dist文件夹以及web3.min.js的原因。

之前的文章《以太开发交互实战》也有提供了下载缺失包的地址，但是下载下来的web3.min.js很可能是0.20.6版本的。因为根据当前1.0官方文档进行使用，很多方法运行会出现找不到此方法的错误信息。而我们的package.json的web3的版本又是"^1.0.0-beta.34"，所以干脆直接去下载1.0.0-beta.34版本的缺失包使用，还可以就着1.0版本的文档食用。

1.1 下载1.0.0-beta.34版本的web3.min.js

首先进入https://github.com/ethereum/web3.js，点击Branch，切换到Tags选项，点击v1.0.0-beta.34，然后download代码，将dist文件夹拷贝到自己项目的moudles的web3文件夹下即可。

2. 使用web3.js查询以太币及代币余额以及进行以太币和代币转账

2.1 在私链和主链上查询以太币及代币余额

查询类方法在私链和主链上的方法都是一样的，说明以下几点：

• 主链地址。可以去infura申请

• contractAbi。合约的abi。可以去https://etherscan.io获取，如果代币合约提供了code，就会有abi

// 引入web3var Web3 = require('web3');if (typeof web3 !== 'undefined') {web3 = new Web3(web3.currentProvider);} else {// web3 = new Web3(new Web3.providers.HttpProvider("http://localhost:7545"));web3 = new Web3(new Web3.providers.HttpProvider("https://mainnet.infura.io/yourAddress"));}// 定义合约abivar contractAbi = [{"constant":true,"inputs":[],"name":"mintingFinished","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"name","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_spender","type":"address"},{"name":"_value","type":"uint256"}],"name":"approve","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"totalSupply","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_from","type":"address"},{"name":"_to","type":"address"},{"name":"_value","type":"uint256"}],"name":"transferFrom","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"decimals","outputs":[{"name":"","type":"uint8"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"cap","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[],"name":"unpause","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"name":"_to","type":"address"},{"name":"_amount","type":"uint256"}],"name":"mint","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"name":"_value","type":"uint256"}],"name":"burn","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"paused","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_spender","type":"address"},{"name":"_subtractedValue","type":"uint256"}],"name":"decreaseApproval","outputs":[{"name":"success","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"name":"_owner","type":"address"}],"name":"balanceOf","outputs":[{"name":"balance","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[],"name":"finishMinting","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[],"name":"pause","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"owner","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"symbol","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_to","type":"address"},{"name":"_value","type":"uint256"}],"name":"transfer","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"name":"_spender","type":"address"},{"name":"_addedValue","type":"uint256"}],"name":"increaseApproval","outputs":[{"name":"success","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"name":"_owner","type":"address"},{"name":"_spender","type":"address"}],"name":"allowance","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"newOwner","type":"address"}],"name":"transferOwnership","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"inputs":[],"payable":false,"stateMutability":"nonpayable","type":"constructor"},{"anonymous":false,"inputs":[{"indexed":true,"name":"burner","type":"address"},{"indexed":false,"name":"value","type":"uint256"}],"name":"Burn","type":"event"},{"anonymous":false,"inputs":[],"name":"Pause","type":"event"},{"anonymous":false,"inputs":[],"name":"Unpause","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"name":"to","type":"address"},{"indexed":false,"name":"amount","type":"uint256"}],"name":"Mint","type":"event"},{"anonymous":false,"inputs":[],"name":"MintFinished","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"name":"owner","type":"address"},{"indexed":true,"name":"spender","type":"address"},{"indexed":false,"name":"value","type":"uint256"}],"name":"Approval","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"name":"from","type":"address"},{"indexed":true,"name":"to","type":"address"},{"indexed":false,"name":"value","type":"uint256"}],"name":"Transfer","type":"event"}];// 合约地址var contractAddress = "0x7FCCF800568747b178c6cBbe4Bf3d147df75ac61";// 账号var currentAccount = "0x4e9d5c58d8d6f02FFe5A6EF10CB804FfFB556bBb";// 定义合约var myContract = new web3.eth.Contract(contractAbi, contractAddress, {from: currentAccount, // default from addressgasPrice: '10000000000' // default gas price in wei, 10 gwei in this case});// 查询以太币余额web3.eth.getBalance(currentAccount).then(console.log);// 查看某个账号的代币余额myContract.methods.balanceOf(contractAddress).call({from: currentAccount}, function(error, result){if(!error) {console.log(result);} else {console.log(error);}});

举一反三，这里还可以查询代币的名称，符号，小数位，发行总量等等，因为代币合约一般都符合ERC标准，都有这些基本方法。甚至如果你有合约代码和abi，还可以调用合约的其他方法，当然调用有些方法需要权限及前置条件。

// 获得代币名称myContract.methods.name().call({from: currentAccount}, function(error, result){if(!error) {console.log(result);} else {console.log(error);}});// 获取代币符号myContract.methods.symbol().call({from: currentAccount}, function(error, result){if(!error) {console.log(result);} else {console.log(error);}});// 获取代币总量myContract.methods.totalSupply().call({from: currentAccount}, function(error, result){if(!error) {console.log(result);} else {console.log(error);}});// 查看某个账号允许另一个账号可使用的代币数量myContract.methods.allowance(sender, spender).call({from: currentAccount}, function(error, result){if(!error) {console.log(result);} else {console.log(error);}});

2.2 在私链上转账以太币及代币

// 以太币转账web3.eth.sendTransaction({from: currentAccount,to: receiverAccount,value: '1000000000000000'}).then(function(receipt){console.log(receipt);});// 代币转账myContract.methods.transfer(to, amount).send({from: currentAccount}), function(error, transactionHash){if(!error) {console.log('transactionHash is ' + transactionHash);} else {console.log(error);}});

2.2 在主链上转账以太币及代币

上面的方法只适用于私链。因为你在私链的账户在本地是有私钥的。而在主链上要进行写入数据的方法，是需要获取账户的私钥并对交易进行签名的，所以要用到web3.eth.sendSignedTransaction方法。

文档http://web3js.readthedocs.io/en/1.0/web3-eth.html#sendsignedtransaction

方法稍微有点复杂，建议先查看底部的参考文章。因为有些重复的内容这里就不再解释了。

需要npm安裝'ethereumjs-tx'

npm install ethereumjs-tx

以太币转账

// 引入ethereumjs-txvar Tx = require('ethereumjs-tx');// 以太币转账    // 先获取当前账号交易的nonceweb3.eth.getTransactionCount(currentAccount, web3.eth.defaultBlock.pending).then(function(nonce){// 获取交易数据var txData = {// nonce每次++，以免覆盖之前pending中的交易nonce: web3.utils.toHex(nonce++),// 设置gasLimit和gasPricegasLimit: web3.utils.toHex(99000),gasPrice: web3.utils.toHex(10e9),// 要转账的哪个账号  to: '0x3b11f5CAB8362807273e1680890A802c5F1B15a8',// 从哪个账号转from: currentAccount,// 0.001 以太币value: web3.utils.toHex(10e14),data: ''}var tx = new Tx(txData);// 引入私钥，并转换为16进制const privateKey = new Buffer('your account privateKey', 'hex');// 用私钥签署交易tx.sign(privateKey);// 序列化var serializedTx = tx.serialize().toString('hex');web3.eth.sendSignedTransaction('0x' + serializedTx.toString('hex'), function(err, hash) {if (!err) {console.log(hash);} else {console.error(err);}});});

代币转账

// 补齐64位，不够前面用0补齐function addPreZero(num){var t = (num+'').length,s = '';for(var i=0; i<64-t; i++){s += '0';}return s+num;}web3.eth.getTransactionCount(currentAccount, web3.eth.defaultBlock.pending).then(function(nonce){// 获取交易数据var txData = {nonce: web3.utils.toHex(nonce++),gasLimit: web3.utils.toHex(99000),gasPrice: web3.utils.toHex(10e9),// 注意这里是代币合约地址    to: contractAddress,from: currentAccount,// 调用合约转账value这里留空value: '0x00',// data的组成，由：0x + 要调用的合约方法的function signature + 要传递的方法参数，每个参数都为64位(对transfer来说，第一个是接收人的地址去掉0x，第二个是代币数量的16进制表示，去掉前面0x，然后补齐为64位)data: '0x' + 'a9059cbb' + addPreZero('3b11f5CAB8362807273e1680890A802c5F1B15a8') + addPreZero(web3.utils.toHex(1000000000000000000).substr(2))}var tx = new Tx(txData);const privateKey = new Buffer('your account privateKey', 'hex');tx.sign(privateKey);var serializedTx = tx.serialize().toString('hex');web3.eth.sendSignedTransaction('0x' + serializedTx.toString('hex'), function(err, hash) {if (!err) {console.log(hash);} else {console.error(err);}});});

 原文出处