Express.js CORS OPTIONS Endpoint

server.js

var express = require('express'),
    app = express();

// More variables initialized...
// More routes, settings, etc.

// This is the OPTIONS endpoint
app.options('*', function (req, res, next) {
    origin = req.headers.origin;
    if (origin == undefined) {
        origin = '*';
    }
    res.header({'Cache-Control': 'no-store'});
    res.header({'Pragma': 'no-cache'});
    res.header({'Access-Control-Allow-Origin': origin});
    res.header({'Access-Control-Allow-Methods': 'GET, POST, PUT, DELETE, HEAD, OPTIONS'});
    res.header({'Access-Control-Allow-Headers': 'Origin, X-Requested-With, Content-Type, Accept, Authorization'});
    if (origin != '*') {
        res.header({'Access-Control-Allow-Credentials': true});
    } else {
        res.header({'Access-Control-Allow-Credentials': false});
    }
    res.status(200);
    next();
});