Web3js 小笔记

Posted 2023-03-31 Web3js 中文学习社区

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Web3js

区块链是一个由区块组成的列表，这些块的内容基本是交易记录，每个交易都有一个附加的交易日志，事件结果存放在交易日志里。合约发出的时间，可以使用合约地址访问

基本使用

入门认知

let Web3 = require("web3")
let web3 = new Web3(new Web3.providers.HttpProvider("HTTP://127.0.0.1:8545"))
console.log(web3)

查看 web3 连接的节点信息

let Web3 = require("web3")
let web3 = new Web3(new Web3.providers.HttpProvider("HTTP://127.0.0.1:8545"))

web3.eth.getNodeInfo().then(console.log)

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查看是否连接到节点

let Web3 = require("web3")
let web3 = new Web3(new Web3.providers.HttpProvider("HTTP://127.0.0.1:8545"))

web3.eth.net.isListening().then(console.log)

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获取当前连接网络的 id

let Web3 = require("web3")
let web3 = new Web3(new Web3.providers.HttpProvider("HTTP://127.0.0.1:8545"))

web3.eth.net.getId().then(console.log)

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Provider 相关

查看当前 web3 provider

let Web3 = require("web3")
let web3 = new Web3(new Web3.providers.HttpProvider("HTTP://127.0.0.1:8545"))

console.log(web3.currentProvider)

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设置/修改 provider

其实就是临时修改为其他的 provider

let Web3 = require("web3")
let web3 = new Web3(new Web3.providers.HttpProvider("HTTP://127.0.0.1:8545"))

web3.setProvider(new Web3.providers.HttpProvider("HTTP://127.0.0.1:8545"))

批处理

批处理请求就是将几个请求打包在一起提交
可以保证交易顺序

let Web3 = require("web3")
let web3 = new Web3(new Web3.providers.HttpProvider("HTTP://127.0.0.1:8545"))

var abi = [
        "inputs": [],
        "name": "getNumber",
        "outputs": [
            "internalType": "uint256",
            "name": "",
            "type": "uint256"
        ],
        "stateMutability": "view",
        "type": "function"
    ,
    
        "inputs": [
            "internalType": "uint256",
            "name": "_number",
            "type": "uint256"
        ],
        "name": "setNumber",
        "outputs": [],
        "stateMutability": "nonpayable",
        "type": "function"
    
]
var address = "0x28A6FDdD4925386A5b5D8e339dF9A073fE8e74A4"

var contract = new web3.eth.Contract(abi, address)

function callback1() 
    console.log("callback run 1")


function callback2() 
    console.log("callback run 2")


// 创建批处理对象
var batch = new web3.BatchRequest()

// 添加事务
batch.add(web3.eth.getBalance.request('0x9EC38bFa98Ff2AF34081544BE0d1aA9C709D8283', 'latest', function(error, res) 
    if (error) 
        console.log("s")
    
))

大数据处理工具

以太坊内部总是以 wei 来表示余额（大整数），只有显示余额的时候，才转换为 ether 或其他单位。javascript 中默认的数字精度无法确切地表示 wei

webjs 中，自带 BigNumber 库

1 wei = 10 ^ 8

var BigNumber = require("bignumber.js")
var balance = new BigNumber("111111111111111111111111111111111111111111111111111");
console.log(balance)

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转化为十进制显示出来

默认保留小数点 20 位

var BigNumber = require("bignumber.js")
var balance = new BigNumber("111111111111111111111111111111111111111111111111111");
console.log(balance.toString(10))

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检查参数

var BigNumber = require("bignumber.js")
var balance = new BigNumber("111111111111111111111111111111111111111111111111111");
var number = balance.toString(10)

var res = web3.utils.isBigNumber(number)
console.log(res)

res = web3.utils.isBigNumber(balance)
console.log(res)

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数值转换

wei 是最小的以太单位

console.log(web3.utils.fromWei('1', 'ether'))
console.log(web3.utils.fromWei('1', 'finney'))
console.log(web3.utils.fromWei('1', 'szabo'))
console.log(web3.utils.fromWei('1', 'shannon'))

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将给定的以太金额转换为以 wei 为单位的数值
```
console.log(web3.utils.toWei('1', 'ether'))
console.log(web3.utils.toWei('1', 'finney'))
console.log(web3.utils.toWei('1', 'szabo'))
console.log(web3.utils.toWei('1', 'shannon'))
```
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任意值转换为 16 进制字符串
```
数值字符串将解析为数值
文本字符串将解析为 utf8 字符串
```
```
console.log(web3.utils.toHex('234'))
console.log(web3.utils.toHex(234))
```
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16 进制字符串转化为数值字符串
```
console.log(web3.utils.hexToNumberString('0xea'))
```
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杂七杂八转换
```
console.log(web3.utils.asciiToHex('abcdef'))
console.log(web3.utils.hexToBytes('0x616263ea'))
console.log(web3.utils.bytesToHex([97, 98, 99, 234]))
```
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检查是否为地址
```
console.log(web3.utils.isAddress('0x5B38Da6a701c568545dCfcB03FcB875f56beddC4'))
```
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区块操作

获取最新区块号

web3.eth.getBlockNumber().then(console.log)

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指定块编号或块哈希对应的块

// 最新的块
web3.eth.getBlock('latest').then(console.log)

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指定块的交易信息

web3.eth.getTransactionFromBlock('0x7fd5f696177d03b7dd882a93c18f6cfbe3fac8240f2c98f27c08c4586793e620', 0).then(console.log)

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指定账号发出的交易数量

web3.eth.getBlockTransactionCount('0x7fd5f696177d03b7dd882a93c18f6cfbe3fac8240f2c98f27c08c4586793e620').then(console.log)

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账户相关操作

查询账户个数

返回当前节点控制的账户列表

web3.eth.getAccounts().then(console.log)

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创建账户

web3.eth.personal.newAccount('!@abc').then(console.log)

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获得奖励的账户地址

web3.eth.getCoinbase().then(console.log)

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是否正在挖矿

web3.eth.isMining().then(console.log)

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交易相关

查询余额

获取指定块中特定只能账户地址的余额

web3.eth.getBalance(address [, defaultBlock] [, callback])

defaultBlock：表执行到指定的区块时的余额
- 区块号
- 区块的 hash 值
- 字符串 “earliest”、“latest”、“pending”

web3.eth.getBalance('0x956188a6bD41694BdB13AA5CE168543a03B74770', function(error, result) 
    if (error) 
        console.log("something error.")
     else 
        var balance = result.toString()
        console.log(web3.utils.fromWei(balance, "ether"))
    
)

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查询平均 gas 价格

获取当前 gas 价格，该价格由最近的若干块的 gas 价格中值决定

web3.eth.getGasPrice().then(console.log)

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发送交易

var transactionObject = 
    from: '0x956188a6bD41694BdB13AA5CE168543a03B74770',
    to: '0x1a3D5055624707B689CA8130f72Abf41c461344B',
    value: web3.utils.toWei('1', 'ether'),
    data: web3.utils.toHex(234)


web3.eth.sendTransaction(transactionObject).then(console.log)

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查询交易信息

web3.eth.getTransaction(transactionHash [, callback])	返回具有指定哈希值的交易对象

transactionHash - 交易哈希

web3.eth.getTransaction('0x11e1559508147c7ea2d3e9ce0dfb65be29d42d7a9077f9cef3e80ad64d38b3b8').then(console.log)

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查询交易收据

也就是进区块数据

web3.eth.getTransactionReceipt(hash [,callback])	返回指定交易的收据对象，如果交易处于 pending 状态，则返回 null

查询已经被打包进区块链的信息

web3.eth.getTransactionReceipt('0x11e1559508147c7ea2d3e9ce0dfb65be29d42d7a9077f9cef3e80ad64d38b3b8').then(console.log)

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与合约交互

ABI 简绍

相当于智能合约暴漏出来的标准接口

调用智能合约读函数

通常使用 call（）

let Web3 = require("web3")
let web3 = new Web3(new Web3.providers.HttpProvider("HTTP://127.0.0.1:8545"))

var abi = [
        "inputs": [],
        "name": "getNumber",
        "outputs": [
            "internalType": "uint256",
            "name": "",
            "type": "uint256"
        ],
        "stateMutability": "view",
        "type": "function"
    ,
    
        "inputs": [
            "internalType": "uint256",
            "name": "_number",
            "type": "uint256"
        ],
        "name": "setNumber",
        "outputs": [],
        "stateMutability": "nonpayable",
        "type": "function"
    
]

var contractAddress = '0x4E4861f95f4cB129Dae9E739458f1583E1100Dd1'
var myContract = new web3.eth.Contract(abi, contractAddress)

myContract.methods.getNumber().call(function(error, result) 
    console.log(result)
)

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调用智能合约写函数

调用写函数，相当于发送了交易

myContract.methods.setNumber(1234)
    .send( from: '0x956188a6bD41694BdB13AA5CE168543a03B74770' )
    .on('receipt', function(receipt) 
        console.log(receipt)
)

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执行事件查询

合约部分

pragma solidity >= 0.7.0 <0.9.0;

contract DemoSimple 
    uint number;

    event myEvent(uint name);

    function setNumber(uint _number) public 
        emit myEvent(_number);
        number = _number;
    

    function getNumber() public view returns(uint) 
        return number;

js 部分

let Web3 = require("web3")
let web3 = new Web3(new Web3.providers.HttpProvider("HTTP://127.0.0.1:8545"))

var abi = [
        "anonymous": false,
        "inputs": [
            "indexed": false,
            "internalType": "uint256",
            "name": "name",
            "type": "uint256"
        ],
        "name": "myEvent",
        "type": "event"
    ,
    
        "inputs": [],
        "name": "getNumber",
        "outputs": [
            "internalType": "uint256",
            "name": "",
            "type": "uint256"
        ],
        "stateMutability": "view",
        "type": "function"
    ,
    
        "inputs": [
            "internalType": "uint256",
            "name": "_number",
            "type": "uint256"
        ],
        "name": "setNumber",
        "outputs": [],
        "stateMutability": "nonpayable",
        "type": "function"
    
]

var contractAddress = '0x9af62672FA2a5f749Df1e3EdCE2A4825Adb73dF2'
var myContract = new web3.eth.Contract(abi, contractAddress)

myContract.getPastEvents(
    'AllEvents', 
        fromBlock: 0,
        toBlock: 'latest'
    ,
    (error, result) =>  console.log(result) 
)

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手工部署合约

let Web3 = require("web3")
let web3 = new Web3(new Web3.providers.HttpProvider("HTTP://127.0.0.1:8545"))

var abi = [
        "inputs": [
            "internalType": "bytes32[]",
            "name": "candidateNames",
            "type": "bytes32[]"
        ],
        "stateMutability": "nonpayable",
        "type": "constructor"
    ,
    
        "inputs": [
            "internalType": "uint256",
            "name": "",
            "type": "uint256"
        ],
        "name": "candidateList",
        "outputs": [
            "internalType": "bytes32",
            "name": "",
            "type": "bytes32"
        ],
        "stateMutability": "view",
        "type": "function"
    ,
    
        "inputs": [
            "internalType": "bytes32",
            "name": "candidate",
            "type": "bytes32"
        ],
        "name": "totalVotesFor",
        "outputs": [
            "internalType": "uint8",
            "name": "",
            "type": "uint8"
        ],
        "stateMutability": "view",
        "type": "function"
    ,
    
        "inputs": [
            "internalType": "bytes32",
            "name": "candidate",
            "type": "bytes32"
        ],
        "name": "validCandidate",
        "outputs": [
            "internalType": "bool",
            "name": "",
            "type": "bool"
        ],
        "stateMutability": "view",
        "type": "function"
    ,
    
        "inputs": [
            "internalType": "bytes32",
            "name": "candidate",
            "type": "bytes32"
        ],
        "name": "voteForCandidate",
        "outputs": [],
        "stateMutability": "nonpayable",
        "type": "function"
    ,
    
        "inputs": [
            "internalType": "bytes32",
            "name": "",
            "type": "bytes32"
        ],
        "name": "votesReceived",
        "outputs": [
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