The Hash
class is a utility for creating hash digests of data. It can be used in one of two ways:
- As a
stream
that is both readable and writable, where data is written to produce a computed hash digest on the readable side, or - Using the
hash.update()
andhash.digest()
methods to produce the computed hash.
The createHash method is used to create Hash
instances. Hash
objects are not to be created directly using the new
keyword.
Example: Using Hash
objects as streams:
const {
createHash,
} = await import('node:crypto');
const hash = createHash('sha256');
hash.on('readable', () => {
// Only one element is going to be produced by the
// hash stream.
const data = hash.read();
if (data) {
console.log(data.toString('hex'));
// Prints:
// 6a2da20943931e9834fc12cfe5bb47bbd9ae43489a30726962b576f4e3993e50
}
});
hash.write('some data to hash');
hash.end();
Example: Using Hash
and piped streams:
import { createReadStream } from 'node:fs';
import { stdout } from 'node:process';
const { createHash } = await import('node:crypto');
const hash = createHash('sha256');
const input = createReadStream('test.js');
input.pipe(hash).setEncoding('hex').pipe(stdout);
Example: Using the hash.update()
and hash.digest()
methods:
const {
createHash,
} = await import('node:crypto');
const hash = createHash('sha256');
hash.update('some data to hash');
console.log(hash.digest('hex'));
// Prints:
// 6a2da20943931e9834fc12cfe5bb47bbd9ae43489a30726962b576f4e3993e50