hash.copy([options])

• options <Object> stream.transform 选项

  ¥options <Object> stream.transform options

• 返回：<Hash>

  ¥Returns: <Hash>

创建新的 Hash 对象，其中包含当前 Hash 对象的内部状态的深层副本。

¥Creates a new Hash object that contains a deep copy of the internal state of the current Hash object.

可选的 options 参数控制流的行为。对于 XOF 哈希函数（例如 'shake256'），可以使用 outputLength 选项指定所需的输出长度（以字节为单位）。

¥The optional options argument controls stream behavior. For XOF hash functions such as 'shake256', the outputLength option can be used to specify the desired output length in bytes.

在调用 hash.digest() 方法后尝试复制 Hash 对象时会引发错误。

¥An error is thrown when an attempt is made to copy the Hash object after its hash.digest() method has been called.

// Calculate a rolling hash.
const {
  createHash,
} = await import('node:crypto');

const hash = createHash('sha256');

hash.update('one');
console.log(hash.copy().digest('hex'));

hash.update('two');
console.log(hash.copy().digest('hex'));

hash.update('three');
console.log(hash.copy().digest('hex'));

// Etc.// Calculate a rolling hash.
const {
  createHash,
} = require('node:crypto');

const hash = createHash('sha256');

hash.update('one');
console.log(hash.copy().digest('hex'));

hash.update('two');
console.log(hash.copy().digest('hex'));

hash.update('three');
console.log(hash.copy().digest('hex'));

// Etc.拷贝