CORS

cors.js

function handleCors(req, res, callback) {

    res.setHeader('Access-Control-Allow-Origin', '*')
    res.setHeader('Access-Control-Allow-Methods', 'GET, POST, PUT, DELETE,OPTIONS');
    res.setHeader('Access-Control-Allow-Headers', 'Authorization');

    // CORS OPTIONS request, simply return 200
    if (req.method == 'OPTIONS') {
        res.statusCode = 200;
        res.end();
        callback.onOptions();
        return;
    }

    callback.onContinue();