server.js

const express = require("express");
const cors = require("cors");
const app = express();

/* -------------------------------------------------------------------------- */

app.get("/no-cors", (req, res) => {
  console.info("GET /no-cors");
  res.json({
    text: "You should not see this via a CORS request."
  });
});

/* -------------------------------------------------------------------------- */

app.head("/simple-cors", cors(), (req, res) => {
  console.info("HEAD /simple-cors");
  res.sendStatus(204);
});
app.get("/simple-cors", cors(), (req, res) => {
  console.info("GET /simple-cors");
  res.json({
    text: "Simple CORS requests are working. [GET]"
  });
});
app.post("/simple-cors", cors(), (req, res) => {
  console.info("POST /simple-cors");
  res.json({
    text: "Simple CORS requests are working. [POST]"
  });
});

/* -------------------------------------------------------------------------- */

app.options("/complex-cors", cors());
app.delete("/complex-cors", cors(), (req, res) => {
  console.info("DELETE /complex-cors");
  res.json({
    text: "Complex CORS requests are working. [DELETE]"
  });
});

/* -------------------------------------------------------------------------- */

const issue2options = {
  origin: true,
  methods: ["POST"],
  credentials: true,
  maxAge: 3600
};
app.options("/issue-2", cors(issue2options));
app.post("/issue-2", cors(issue2options), (req, res) => {
  console.info("POST /issue-2");
  res.json({
    text: "Issue #2 is fixed."
  });
});

/* -------------------------------------------------------------------------- */

if (!module.parent) {
  const port = process.env.PORT || 3001;

  app.listen(port, () => {
    console.log("Express server listening on port " + port + ".");
  });
}