let jwt = require('jwt-simple');
let payload = { foo: 'bar' };
let secret = 'xxx';
// HS256 secrets are typically 128-bit random strings, for example hex-encoded:
// let secret = Buffer.from('fe1a1915a379f3be5394b64d14794932', 'hex')
// encode
let token = jwt.encode(payload, secret);
// decode
let decoded = jwt.decode(token, secret);
console.log(decoded); //=> { foo: 'bar' }

/*
 * jwt.decode(token, key, noVerify, algorithm)
 */
// decode, by default the signature of the token is verified
let decoded = jwt.decode(token, secret);
console.log(decoded); //=> { foo: 'bar' }
// decode without verify the signature of the token,
// be sure to KNOW WHAT ARE YOU DOING because not verify the signature
// means you can't be sure that someone hasn't modified the token payload
let decoded = jwt.decode(token, secret, true);
console.log(decoded); //=> { foo: 'bar' }
// decode with a specific algorithm (not using the algorithm described in the token payload)
let decoded = jwt.decode(token, secret, false, 'HS256');
console.log(decoded); //=> { foo: 'bar' }

// encode using HS512
jwt.encode(payload, secret, 'HS512')