Node: Read data, transform it and write into file using streams and pipe
<p>I try to read a string from a text file, encode it and save into a file. I wanna use <code>pipe</code> in order to transfer <code>hash</code> from <code>ReadStream</code> to <code>WriteStream</code>. But I don't know how to transform the changed data. My code:</p>

<pre><code>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'))
});
</code></pre>