CODE EXAMPLE FOR JAVASCRIPT

access-to-xmlhttprequest-has-been-blocked-by-cors-policy

app.use(function (req, res, next) {
    //Enabling CORS
    res.header("Access-Control-Allow-Origin", "*");
    res.header("Access-Control-Allow-Methods", "GET,HEAD,OPTIONS,POST,PUT");
    res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, 
    Accept, x-client-key, x-client-token, x-client-secret, Authorization");
      next();
    });