原文在这里
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)进行许可，使用时请注明出处。
Author: mengbin
blog: mengbin
Github: mengbin92
cnblogs: 恋水无意
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