node-forge how to read a private rsa key from file

Read pkey as bytes and use forge.pki.privateKeyFromPem.

Working code:

const forge = require('node-forge');
const fs = require('fs');
const path = require('path');
let pkey = fs.readFileSync(path.join(__dirname, 'test.key'));
let privateKey = forge.pki.privateKeyFromPem(pkey);