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

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。

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。

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);}});

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
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