静态方法：Buffer.stringLength(input[, encoding])

🌐 Static method: Buffer.stringLength(input[, encoding])

• input <Buffer> | <ArrayBuffer> | <TypedArray> 将被解码的字节。
• encoding <string> 字符编码 input 会被解码为。默认： 'utf8'。
• 返回：<integer>

返回字符串的长度（以 UTF-16 代码单元为单位），这是 buf.toString(encoding) 对相同字节产生的结果，而不对它们进行解码。这是 Buffer.byteLength() 的对应操作，Buffer.byteLength() 返回字符串编码后的字节数。

🌐 Returns the length, in UTF-16 code units, of the string that buf.toString(encoding) would produce for the same bytes, without decoding them. This is the counterpart of Buffer.byteLength(), which returns the number of bytes a string would encode to.

对于 'utf8'，无效的字节序列会按解码方式进行计数：每个最长的无效子序列会变成一个 U+FFFD 替换字符。对于其他所有编码，结果只根据 input.byteLength 来计算。

🌐 For 'utf8', invalid byte sequences are counted as they would be decoded: each maximal invalid subsequence becomes one U+FFFD replacement character. For every other encoding the result is computed from input.byteLength alone.

一个分离的ArrayBuffer，或一个由它支持的TypedArray，被视为空的。

🌐 A detached ArrayBuffer, or a TypedArray backed by one, is treated as empty.

结果没有上限：在解码之前，将其与 buffer.constants.MAX_STRING_LENGTH 比较，以了解解码是否能成功。一个由 n 代码单元组成的字符串占用的内存在 n 到 2 * n 字节之间。

🌐 The result is not capped: compare it with buffer.constants.MAX_STRING_LENGTH before decoding to know whether the decode can succeed at all. A string of n code units occupies between n and 2 * n bytes of memory.

import { Buffer, constants } from 'node:buffer';

const buf = Buffer.from('€ 100', 'utf8');

console.log(Buffer.stringLength(buf));
// Prints: 5
console.log(Buffer.stringLength(buf, 'hex'));
// Prints: 14
console.log(Buffer.stringLength(buf) <= constants.MAX_STRING_LENGTH);
// Prints: trueconst { Buffer, constants } = require('node:buffer');

const buf = Buffer.from('€ 100', 'utf8');

console.log(Buffer.stringLength(buf));
// Prints: 5
console.log(Buffer.stringLength(buf, 'hex'));
// Prints: 14
console.log(Buffer.stringLength(buf) <= constants.MAX_STRING_LENGTH);
// Prints: true拷贝