Using SHA-256 with NodeJS Crypto - node.js

Question

I'm trying to hash a variable in NodeJS like so:
var crypto = require('crypto');
var hash = crypto.createHash('sha256');
var code = 'bacon';
code = hash.update(code);
code = hash.digest(code);
console.log(code);
But looks like I have misunderstood the docs as the console.log doesn't log a hashed version of bacon but just some information about SlowBuffer.
What's the correct way to do this?

Answer 1

base64:
var crypto = require('crypto');
const hash = crypto.createHash('sha256').update(input).digest('base64');
hex:
var crypto = require('crypto')
const hash = crypto.createHash('sha256').update(input).digest('hex');

Answer 2

nodejs (8) ref
const crypto = require('crypto');
const hash = crypto.createHash('sha256');
hash.on('readable', () => {
const data = hash.read();
if (data) {
console.log(data.toString('hex'));
// Prints:
// 6a2da20943931e9834fc12cfe5bb47bbd9ae43489a30726962b576f4e3993e50
}
});
hash.write('some data to hash');
hash.end();

Answer 3

you can use, like this, in here create a reset token (resetToken), this token is used to create a hex version.in database, you can store hex version.
// Generate token
const resetToken = crypto.randomBytes(20).toString('hex');
// Hash token and set to resetPasswordToken field
this.resetPasswordToken = crypto
.createHash('sha256')
.update(resetToken)
.digest('hex');
console.log(resetToken )

Answer 4

Similar to the answers above, but this shows how to do multiple writes; for example if you read line-by-line from a file and then add each line to the hash computation as a separate operation.
In my example, I also trim newlines / skip empty lines (optional):
const {createHash} = require('crypto');
// lines: array of strings
function computeSHA256(lines) {
const hash = createHash('sha256');
for (let i = 0; i < lines.length; i++) {
const line = lines[i].trim(); // remove leading/trailing whitespace
if (line === '') continue; // skip empty lines
hash.write(line); // write a single line to the buffer
}
return hash.digest('base64'); // returns hash as string
}
I use this code ensure generated lines of a file aren't edited by someone manually. To do this, I write the lines out, append a line like sha256:<hash> with the sha265-sum, and then, upon next run, verify the hash of those lines matches said sha265-sum.