fineui/src/polyfill/event.js

(function () {
    if (typeof window.CustomEvent === "function") return false; // If not IE

    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;
}());