Mashape/mockbin

module.exports = (req, res, next) => {
    // default values
    const cors = {
        origin: "*",
        headers: Object.keys(req.headers).join(),
        methods: req.method,
    };

    if (req.headers.origin) {
        cors.origin = req.headers.origin;
    }

    if (req.headers["access-control-request-headers"]) {
        cors.headers = req.headers["access-control-request-headers"];
    }

    if (req.headers["access-control-request-method"]) {
        cors.methods = req.headers["access-control-request-method"];
    }

    res.set({
        "Access-Control-Allow-Origin": cors.origin,
        "Access-Control-Allow-Methods": cors.methods,
        "Access-Control-Allow-Headers": cors.headers,
        "Access-Control-Allow-Credentials": "true",
    });

    next();
};