静态方法：Buffer.byteLength(string[, encoding])

¥Static method: Buffer.byteLength(string[, encoding])

• string <string> | <Buffer> | <TypedArray> | <DataView> | <ArrayBuffer> | <SharedArrayBuffer> 用于计算长度的值。

  ¥string <string> | <Buffer> | <TypedArray> | <DataView> | <ArrayBuffer> | <SharedArrayBuffer> A value to calculate the length of.

• encoding <string> 如果 string 是字符串，则这就是它的编码。默认值：'utf8'。

  ¥encoding <string> If string is a string, this is its encoding. Default: 'utf8'.

• 返回：<integer> string 中包含的字节数。

  ¥Returns: <integer> The number of bytes contained within string.

使用 encoding 编码时返回字符串的字节长度。这与 String.prototype.length 不同，String.prototype.length 不考虑用于将字符串转换为字节的编码。

¥Returns the byte length of a string when encoded using encoding. This is not the same as String.prototype.length, which does not account for the encoding that is used to convert the string into bytes.

对于 'base64'、'base64url' 和 'hex'，此函数假定输入有效。对于包含非 base64/hex 编码数据（例如空格）的字符串，返回值可能大于从字符串创建的 Buffer 的长度。

¥For 'base64', 'base64url', and 'hex', this function assumes valid input. For strings that contain non-base64/hex-encoded data (e.g. whitespace), the return value might be greater than the length of a Buffer created from the string.

import { Buffer } from 'node:buffer';

const str = '\u00bd + \u00bc = \u00be';

console.log(`${str}: ${str.length} characters, ` +
            `${Buffer.byteLength(str, 'utf8')} bytes`);
// Prints: ½ + ¼ = ¾: 9 characters, 12 bytesconst { Buffer } = require('node:buffer');

const str = '\u00bd + \u00bc = \u00be';

console.log(`${str}: ${str.length} characters, ` +
            `${Buffer.byteLength(str, 'utf8')} bytes`);
// Prints: ½ + ¼ = ¾: 9 characters, 12 bytes拷贝

当 string 是 <Buffer> | <DataView> | <TypedArray> | <ArrayBuffer> | <SharedArrayBuffer> 时，将返回 .byteLength 报告的字节长度。

¥When string is a <Buffer> | <DataView> | <TypedArray> | <ArrayBuffer> | <SharedArrayBuffer>, the byte length as reported by .byteLength is returned.