从问题中引用的片段：
[the Hash类]它是一个既可读又可写的流。写入的数据用于计算哈希。一旦流的可写端结束，使用read（）方法获取计算的哈希摘要。
所以你需要散列一些文本是：

var crypto = require('crypto');

// change to 'md5' if you want an MD5 hash
var hash = crypto.createHash('sha1');

// change to 'binary' if you want a binary hash.
hash.setEncoding('hex');

// the text that you want to hash
hash.write('hello world');

// very important! You cannot read from the stream until you have called end()
hash.end();

// and now you get the resulting hash
var sha1sum = hash.read();

如果你想获取一个文件的哈希值，最好的方法是从文件中创建一个ReadStream，并将其导入哈希值：

var fs = require('fs');
var crypto = require('crypto');

// the file you want to get the hash    
var fd = fs.createReadStream('/some/file/name.txt');
var hash = crypto.createHash('sha1');
hash.setEncoding('hex');

fd.on('end', function() {
    hash.end();
    console.log(hash.read()); // the desired sha1sum
});

// read all file and pipe it (write it) to the hash object
fd.pipe(hash);

ES6版本返回一个Promise作为hash摘要：

function checksumFile(hashName, path) {
  return new Promise((resolve, reject) => {
    const hash = crypto.createHash(hashName);
    const stream = fs.createReadStream(path);
    stream.on('error', err => reject(err));
    stream.on('data', chunk => hash.update(chunk));
    stream.on('end', () => resolve(hash.digest('hex')));
  });
}

卡洛斯的简短回答：

var fs = require('fs')
var crypto = require('crypto')

fs.createReadStream('/some/file/name.txt').
  pipe(crypto.createHash('sha1').setEncoding('hex')).
  on('finish', function () {
    console.log(this.read()) //the hash
  })

进一步的润色，ECMAScript 2015
hash.js：

'use strict';

function checksumFile(algorithm, path) {
  return new Promise(function (resolve, reject) {
    let fs = require('fs');
    let crypto = require('crypto');

    let hash = crypto.createHash(algorithm).setEncoding('hex');
    fs.createReadStream(path)
      .once('error', reject)
      .pipe(hash)
      .once('finish', function () {
        resolve(hash.read());
      });
  });
}

checksumFile('sha1', process.argv[2]).then(function (hash) {
  console.log('hash:', hash);
});

node hash.js hash.js
hash: 9c92ec7acf75f943aac66ca17427a4f038b059da

至少在v10.x之前有效：

node --version
v10.24.1

我成功地使用了Node模块hasha，代码变得非常简洁和简短。它返回一个promise，所以你可以用await来使用它：

const hasha = require('hasha');

const fileHash = await hasha.fromFile(yourFilePath, {algorithm: 'md5'});

var fs = require('fs');
var crypto = require('crypto');
var fd = fs.createReadStream('data.txt');
var hash = crypto.createHash('md5');
hash.setEncoding('hex');
fd.pipe(hash);
hash.on('data', function (data) {
    console.log('# ',data);
});