Custom Event Polyfill From MDN

custom-event-polyfill.js

// custom event polyfill for IE9 - IE11
(function () {
    if (typeof window.CustomEvent !== 'function') {
        function CustomEvent(event, params) {
            params = params || { bubbles: false, cancelable: false, detail: undefined };
            var evt = document.createEvent('CustomEvent');
            evt.initCustomEvent(event, params.bubbles, params.cancelable, params.detail);
            return evt;
        }
        CustomEvent.prototype = window.Event.prototype;
        window.CustomEvent = CustomEvent;
    }
})();