buf.subarray([start[, end]])

• start <integer> 新的 Buffer 将开始的位置。默认值：0。

  ¥start <integer> Where the new Buffer will start. Default: 0.

• end <integer> 新的 Buffer 将结束的位置（不包括在内）。默认值：buf.length。

  ¥end <integer> Where the new Buffer will end (not inclusive). Default: buf.length.

• 返回：<Buffer>

  ¥Returns: <Buffer>

返回一个新的 Buffer，它引用与原始内存相同的内存，但由 start 和 end 索引进行偏移和裁剪。

¥Returns a new Buffer that references the same memory as the original, but offset and cropped by the start and end indexes.

指定 end 大于 buf.length 将返回与 end 等于 buf.length 相同的结果。

¥Specifying end greater than buf.length will return the same result as that of end equal to buf.length.

该方法继承自 TypedArray.prototype.subarray()。

¥This method is inherited from TypedArray.prototype.subarray().

修改新的 Buffer 切片会修改原来 Buffer 中的内存，因为两个对象分配的内存是重叠的。

¥Modifying the new Buffer slice will modify the memory in the original Buffer because the allocated memory of the two objects overlap.

import { Buffer } from 'node:buffer';

// Create a `Buffer` with the ASCII alphabet, take a slice, and modify one byte
// from the original `Buffer`.

const buf1 = Buffer.allocUnsafe(26);

for (let i = 0; i < 26; i++) {
  // 97 is the decimal ASCII value for 'a'.
  buf1[i] = i + 97;
}

const buf2 = buf1.subarray(0, 3);

console.log(buf2.toString('ascii', 0, buf2.length));
// Prints: abc

buf1[0] = 33;

console.log(buf2.toString('ascii', 0, buf2.length));
// Prints: !bcconst { Buffer } = require('node:buffer');

// Create a `Buffer` with the ASCII alphabet, take a slice, and modify one byte
// from the original `Buffer`.

const buf1 = Buffer.allocUnsafe(26);

for (let i = 0; i < 26; i++) {
  // 97 is the decimal ASCII value for 'a'.
  buf1[i] = i + 97;
}

const buf2 = buf1.subarray(0, 3);

console.log(buf2.toString('ascii', 0, buf2.length));
// Prints: abc

buf1[0] = 33;

console.log(buf2.toString('ascii', 0, buf2.length));
// Prints: !bc拷贝

指定负索引会导致相对于 buf 的末尾而不是开头生成切片。

¥Specifying negative indexes causes the slice to be generated relative to the end of buf rather than the beginning.

import { Buffer } from 'node:buffer';

const buf = Buffer.from('buffer');

console.log(buf.subarray(-6, -1).toString());
// Prints: buffe
// (Equivalent to buf.subarray(0, 5).)

console.log(buf.subarray(-6, -2).toString());
// Prints: buff
// (Equivalent to buf.subarray(0, 4).)

console.log(buf.subarray(-5, -2).toString());
// Prints: uff
// (Equivalent to buf.subarray(1, 4).)const { Buffer } = require('node:buffer');

const buf = Buffer.from('buffer');

console.log(buf.subarray(-6, -1).toString());
// Prints: buffe
// (Equivalent to buf.subarray(0, 5).)

console.log(buf.subarray(-6, -2).toString());
// Prints: buff
// (Equivalent to buf.subarray(0, 4).)

console.log(buf.subarray(-5, -2).toString());
// Prints: uff
// (Equivalent to buf.subarray(1, 4).)拷贝