How to get the modulus and exponent of an RSA public key in Node.js

Question

I am creating an ACME client and I need to find the modulus and exponent of my RSA public key, which I generate using the following code:

crypto.generateKeyPairSync('rsa', {
    modulusLength: 4096,
    publicKeyEncoding: {
        type: 'spki',
        format: 'pem'
    },
    privateKeyEncoding: {
        type: 'pkcs8',
        format: 'pem'
    }
});

I need the modulus and exponent, so that I can use them in the JWK section of my JWS:

alg: 'RS256',
jwk: {
    kty: 'RSA',
    e: '...',
    n: '...'
},
nonce,
url: directory.newAccount

I have managed to decode the public key from base64 to hex using the following line, but I am not sure what to do next:

Buffer.from(publicKey, 'base64').toString('hex');

How do I find the modulus and exponent of an RSA public key in Node.js?

---

EDIT 1

I have discovered that Node.js uses the public exponent 65537 by default: Node.js documentation.

Answer 1

It's easy as a piece of cake; it doesn't require 3rd party libraries

import { createPublicKey } from 'crypto'

const pemPublicKey = `-----BEGIN PUBLIC KEY-----
MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAphRAj+tRfbrYwnSFbWrj
...
vQIDAQAB
-----END PUBLIC KEY-----
`
const publicKey = createPublicKey(pemPublicKey)
console.log(publicKey.export({ format: 'jwk' }))

it will return object:

{
  kty: 'RSA',
  n: [modulus string],
  e: [exponent string]
}