Node:通过流和管道读取数据，并将其转换为文件

Question

我尝试从文本文件中读取字符串，对其进行编码并保存到文件中。我想用pipe把hash从ReadStream转移到WriteStream。但我不知道如何转换改变后的数据。我的代码:

const crypto = require('crypto');
const fs = require('fs');
let hash = crypto.createHash('md5');
var rs = fs.createReadStream('./passwords.txt');
var ws = fs.createWriteStream('./new_passwords.txt');

rs.on('data', function(d) {
  hash.update(d);
});
rs.on('end', function(d) {
    console.log(hash.digest('hex'))
});

Answer 1

根据文档，它应该像这样简单:

const fs = require('fs')
const crypto = require('crypto')
const hash = crypto.createHash('md5')
const rs = fs.createReadStream('./plain.txt')
const ws = fs.createWriteStream('./hashed.txt')
rs.pipe(hash).pipe(ws)

Answer 2

var rs = fs.createReadStream('./passwords.txt');
var ws = fs.createWriteStream('./new_passwords.txt');
var Transform = require('stream').Transform;
var transformer = new Transform();
transformer._transform = function(data, encoding, cb) {
 // do transformation
 cb();
}
    rs
    .pipe(transformer)
    .pipe(ws);