Super simple middleware for allowing CORS from express

allowcors.js

app.use(allowCrossDomain); // Use below function as a middleware for your requests

function allowCrossDomain(req, res, next) {
    res.header('Access-Control-Allow-Origin', '*');
    res.header('Access-Control-Allow-Methods', 'GET,PUT,POST,DELETE,OPTIONS');
    res.header('Access-Control-Allow-Headers', 'Content-Type, Authorization, Content-Length, X-Requested-With');

    // intercept OPTIONS method
    if ('OPTIONS' == req.method) {
      res.send(200);
    } else {
      next();
    }
};