web3.js：utils包

孟斯特

发布于 2024-05-17 18:45:09

2120

发布于 2024-05-17 18:45:09

文章被收录于专栏：code人生

原文在这里[1]

介绍

在这个指南中，你将学习到web3 utils包的不同函数，它包含了如何以不同格式生成随机字节，如何在Hex值和数字之间进行转换，哈希函数，地址，打包填充的方法，最后你将看到如何比较区块号。

安装

只安装web3工具包：

$ npm i web3-utils

或者你也可以安装web3库，然后访问web3.utils：

$ npm i web3

导入

有三种不同的方式来导入utils包。

导入完整的web库

// import web3 module
import { Web3 } from "web3";

// no need to initialize a provider
Web3.utils.toHex("web3");
//=> 0x77656233

// initializing  a provider
const web3 = new Web3("https:// eth.llamarpc.com");

// access the utils package
web3.utils.toHex("web3");
//=> 0x77656233

导入utils模块

// import utils module
import { utils } from "web3"; 

// access the utils package
utils.toWei("1", "ether")

导入指定方法

// import toWei and toHex functions
import { toWei, toHex } from"web3-utils";

// usage
toWei("1", "ether")
toHex("")

方法示例

随机Hex和Bytes

// Random bytes in hex format and array format

console.log(web3.utils.randomBytes(32));
/* => array format
Uint8Array(32) [
  251,  70, 124,  65, 203, 180,  92, 234,
  210, 236,  72, 154,  83, 219, 171, 223,
  212, 136, 117, 140,  67, 117,  86,  81,
  234, 245, 148, 186, 175,  83,  98,  78
]
*/

console.log(web3.utils.randomHex(32));
/* => hex string format
0x594386dc9b2e150979416f9b2a093e01f84a37c4f8db5fc1b0d9b1dc83a12c1f
*/

INFO 如果你不给出任何参数，那么这两个函数的默认值都将为32。

转换 - 以太坊面额

我们有两个不同的函数来进行以太坊面额之间的转换。

console.log(web3.utils.fromWei("1", "ether")); 
// 0.000000000000000001

console.log(web3.utils.toWei("1", "ether")); 
// 1_000_000_000_000_000_000

转换Hex变量

// most versatile one
console.log(web3.utils.toHex(10));
// 0xa

console.log(web3.utils.toHex(true));
// 0x01

console.log(web3.utils.numberToHex(10));
// 0xa

console.log(web3.utils.fromDecimal(10));
// 0xa

const arr = new Uint8Array([1, 2, 3, 4]);

console.log(web3.utils.toHex(arr));
// 0x7b2230223a312c2231223a322c2232223a332c2233223a347d

console.log(web3.utils.bytesToHex(arr));
// 0x01020304

转换UTF和ASCII

console.log(web3.utils.utf8ToHex("😊"));
// 0xf09f988a

console.log(web3.utils.fromUtf8("😊"));
// 0xf09f988a

console.log(web3.utils.asciiToHex("😊"));
// 0xd83dde0a

console.log(web3.utils.toUtf8("0xf09f988a"));
// 😊

console.log(web3.utils.hexToUtf8("0xf09f988a"));
// 😊

console.log(web3.utils.hexToString("0xf09f988a"));
// 😊

// emojis are not ASCII character, that's why it won't work
console.log(web3.utils.toAscii("0x4869"));
// Hi

console.log(web3.utils.hexToAscii("0x4869"));
// Hi

转换 - 数字和Bigint

console.log(web3.utils.toNumber("0xa"));
// 10 (number)

console.log(web3.utils.hexToNumber("0xa"));
// 10 (number)

console.log(web3.utils.toDecimal("0xa"));
// 10 (number)

console.log(web3.utils.hexToNumberString("0xa"));
// 10 (string)

console.log(web3.utils.toBigInt("0xa")); 
// 10n (bigint)

哈希函数

// both will return undefined if an empty string is passed as an argument
console.log(web3.utils.sha3("hello web3"));
// 0x6c171485a0138b7b0a49d72b570e1d9c589d42a79ae57329d90671d1ac702d74

console.log(web3.utils.soliditySha3({ type: "string", value: "hello web3" }));
// 0x6c171485a0138b7b0a49d72b570e1d9c589d42a79ae57329d90671d1ac702d74

地址

// isAddress() is deprecated so we can use toCheckSumAddress()
// to see if the hex string we are passing is a correct ethereum address

// passing an address with all characters lowercase
console.log(web3.utils.toChecksumAddress("0xa3286628134bad128faeef82f44e99aa64085c94"));
// 0xA3286628134baD128faeef82F44e99AA64085C94

// passing an wrong address
console.log(web3.utils.toChecksumAddress("0xa3286628134bad128faeef82f44e99aa64085c9"));
// InvalidAddressError: Invalid value given "0xa286628134bad128faeef82f44e99aa64085c94". Error: invalid ethereum address.

打包和填充

// same as abi.encodePacked() in solidity (must be strings)
// converts everything to hex and packs everything without padding
console.log(web3.utils.encodePacked("1", "1", "1"));
// 0x313131


// it will convert the number `10` to hex('a') and add 0s until it's 32 characters long
// the third argument will be the one that will fill/pad the whole hex string, in this case is '0'
console.log(web3.utils.padRight(10, 32, 0));
// 0xa0000000000000000000000000000000

console.log(web3.utils.rightPad(10, 32, 0));
// 0xa0000000000000000000000000000000

console.log(web3.utils.padLeft(10, 32, 0));
// 0x0000000000000000000000000000000a

console.log(web3.utils.leftPad(10, 32, 0));
// 0x0000000000000000000000000000000a

比较区块号

// accepts numbers and formats as well
console.log(web3.utils.compareBlockNumbers("pending", "latest"));
// 1

console.log(web3.utils.compareBlockNumbers("latest", "pending"));
// -1

console.log(web3.utils.compareBlockNumbers("latest", "latest"));
// 0

console.log(web3.utils.compareBlockNumbers(2, 2));
// 0

声明：本作品采用署名-非商业性使用-相同方式共享 4.0 国际 (CC BY-NC-SA 4.0)[2]进行许可，使用时请注明出处。 Author: mengbin[3] blog: mengbin[4] Github: mengbin92[5] cnblogs: 恋水无意[6] 腾讯云开发者社区：孟斯特[7]

References

[1] 这里: https://docs.web3js.org/guides/web3_utils_module/mastering_web3-utils [2] 署名-非商业性使用-相同方式共享 4.0 国际 (CC BY-NC-SA 4.0): https://creativecommons.org/licenses/by-nc-sa/4.0/deed.zh [3] mengbin: mengbin1992@outlook.com [4] mengbin: https://mengbin.top [5] mengbin92: https://mengbin92.github.io/ [6] 恋水无意: https://www.cnblogs.com/lianshuiwuyi/ [7] 孟斯特: https://cloud.tencent.com/developer/user/6649301