Promisify: adhoc promisify

token-verification.js

const jwt = require("jsonwebtoken");

const promisify = fn => (...args) => new Promise((resolve, reject) => {
    fn(...args, (error, value) => {
      if (error) {
        reject(error);
      } else {
        resolve(value);
      }
  });
});

const jwtVerify = promisify(jwt.verify);

const verifyToken = token => jwtVerify(token, CERTIFICATE, { algorithms: ["RS256"] });