First, install the jsonwebtoken package (npmjs.com):

$ npm install jsonwebtoken

Require it at the top of your module:

const jwt = require("jsonwebtoken");

Now, we export a function to do the heavy lifting.

module.exports = function makeToken() {

The session token payload includes claims typical of an OpenID Connect ID token.

• The aud claim indicates who is meant to consume the token
• The iss claim indicates who generated the token
• The sub claim indicates who the token is meant to represent

  const payload = {
    aud: "AUDIENCE_ID",
    iss: "https://example.com/",
    sub: "SUBJECT_ID",
  };

This function will return a signed JSON Web Token - JWT - using the second parameter below as the signing key. This token will need that same value to check the token signature when validated. It will be obvious to some but the "TOKEN_SECRET" value below should be long, random, and never stored in the code.

Note that the jsonwebtoken library can accept plain English time representations.

  return jwt.sign(payload, "TOKEN_SECRET", {
    expiresIn: "1 day",
  });
};

And there you have it, a function that returns a signed token!