ES6 Polyfill if needed
function es6polyfill() {
var js = document.createElement('script');
js.defer = true;
js.src = "https://cdn.polyfill.io/v2/polyfill.js?features='default,Promise,fetch,&flags=gated";
document.head.appendChild(js);
}
window.Promise && window.fetch ? null : es6polyfill