JWT signing with b64:false in node.js

jws.js

const jose = require("node-jose");
const fs = require("fs");

const privateKEY = fs.readFileSync("./newRS256.key", "utf8");
// const publicKEY = fs.readFileSync("./newRS256.key.pub", "utf8");

const keystore = jose.JWK.createKeyStore();

const payload = {
  foo: "test"
};

const jose_header = {
  alg: "RS256",
  b64: false,
  kid: "kid",
  typ: "JOSE"
};

async function sign() {
  const privateJWK = await keystore.add(privateKEY, "pem");
  const signed_jwt = await jose.JWS.createSign(
    {
      fields: jose_header,
      //format: "compact"
      format: "flatten"
    },
    {
      key: privateJWK
    }
  )
    .update(JSON.stringify(payload), "utf8")
    .final();

  return signed_jwt;
}

sign().then(signed => console.log(signed));

newRS256.key

-----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY-----

newRS256.key.pub

-----BEGIN PUBLIC KEY-----
MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA5i0tS/LQd5A5oBBHVlhu
rp+zxhoCHRWn6C6nXRV9KZsWNupU98SSc8TrNuzrGrjys1ri6rg5CtehqB4I5H98
Kv3FHNRBFdtGHWx4wArvE0niq1PFPHgl0QnN0Za7MvIKNeirgEZh2ZI9u7jYcyBU
N8P4iDjja9fUde8ezsSeDG8/qdGgu49m7p0QeybseAbmCxONZF7A+LigUDrx+ZVP
yNrcvmKnxqp+9OwtLK+XY+QH/ctjt837wKcQE8f1KSZCbcDfLsS/aUgQWmrDadc0
vrxSfEef7nr3/wYl2BYdFbYH/CjQ+13ZcrMb4zJnPXNpIZSPEUjn12DS7Id6jJ4e
8wIDAQAB
-----END PUBLIC KEY-----